Temporal and Spatial Changes in Crop Patterns, Use of Inputs and Hydrological Alteration in the Case of Fogera Floodplain, Ethiopia

More than half of the world's population consumes rice. The area under modern rice varieties has expanded, the use of chemical fertilizers and pesticides has increased in various countries. The hydrology of wetlands are also inuenced by its chemical and physical characteristics. Hence, this research focused on temporal and spatial changes in crop patterns, input usage, and hydrological change in Fogera oodplain, with the objectives: a. what are the spatial and temporal trends in crops production pattern? b. What inputs have been used in the past and present to produce rice and other crops? c. What looks like the hydrological alteration of the area? The primary data was gathered through a questionnaire, focus group discussions, interviews, and eld observations. Secondary data from Landsat imageries, SWAT input data, water ow, normalized difference vegetation index, and hydrological alteration of the site were collected. To analyze data, tables, graphs, and charts percentage, mean, and correlation were used. NDVI results indicated that rice crop is growing while other variables are decreasing. articial inputs are currently used but before the introduction of rice were not. Recession farming activities have also diminished wetland. Annual average water ow and rainfall have been trending upward. Flow of water with Nitrogen and Phosphorous has a negative correlation, with Pearson's values − 0.069 and − 0.072, respectively whereas the value 0.242 indicates that nitrogen and phosphorus have a positive relationship. In conclusion, these extended and intensication of farming practices have an impact on the biodiversity of fauna and ora of the area.

To increase rice production and market system, several studies were conducted in the Fogera Wetland. For example, the impact of integrated farmyard fertilizer and inorganic nitrogen (N) and phosphorous (P) fertilizers on rain-fed rice development, produce, and fatal moisture pressure tolerance (Tilahun et al., 2013); pro tability and marketing chain of rice in Fogera Woreda (Astewel 2010); evaluation of the outcome of different time and incidence of hand weeding levels on direct-seeded rice (Agegnehu et al., 2013); and researchers studied the response of rice's produce and produce components to determine the optimal fertilizer levels required for increased grain production of ooded rice (Heluf and Mulugeta 2006). These studies, on the other hand, overlooked the Fogera oodplain wetland's environmental trade-offs and other ecosystem functions.
As a result of rice intensi cation in the wetlands of Fogera areas along the Eastern shore of Lake Tana, this research aims to identify temporal and spatial shifts in crop patterns, input use, and hydrological alteration in the Fogera oodplain. As a result, the following are the study's objectives: a. what are the spatial and temporal trends in crops production pattern in the area? b. What inputs have been used in the past and present to produce rice and other crops? c.
What looks like the hydrological alteration of the area? Fogera Woreda is one of the surplus crop-producing areas, with a high potential for rice production. The oodwaters that collect around Lake Tana and the two major rivers, Rib and Gumara, are channeled through this region. Rivers carry eroded soil from highland to the plains. The soil tends to be rich in nutrients and deep in depth. In the study area, rice is planted on lower slopes where the water table rises to the surface for a long time during the cropping season. Rice is also irrigated with water diverted from streams in a drainage system's upper reaches. The sum of irrigated water, on the other hand, is usually negligible. The primary sources of water for rice plants in Fogera and the surrounding Woredas are rainfall, runoff, and underground water. In the processing of rain-fed rice, bunds are commonly used. During the growing season, the bunds are used to hold oodwater and rainwater out (IPMS, 2005; Abaye, 2007).
On the top left side of the map, Ethiopia is depicted with a geographical map of the Amhara region; on the bottom left side, the Amhara Region and regional zones are depicted; on the right bottom, Fogera Woreda that comprises only 10 biosphere reserve kebeles is depicted; and on the top right side, the study site is depicted.

Sampling and data collection
The research was carried out in the Fogera Wetland on Lake Tana's Eastern Shore. According to the preliminary assessment conducted during a eld visit to some Fogera oodplains, the wetlands of Lake Tana are highly vulnerable to environmental trade-offs as a result of various development activities such as rice intensi cation, shing, sand extraction, and illegal recession cultivation. Fogera is one of the wetland areas surrounding the Lake Tana water body that has large wetlands that are heavily used for rice intensi cation. As a result, the wetland is vulnerable to environmental trade-offs. Besides, the Fogera oodplain currently has the two largest rivers that feed Lake Tana. As a result, the Fogera oodplain has been chosen for further investigation and long-term use of the wetland resource.
There are 27 Kebeles in Fogera Woreda, including Woreta and Amed ber (Alember) area. Sample kebeles were chosen with care for the analysis. The riceproducing kebeles closest to the Lake Tana oodplain are rst identi ed. In this situation, there were ve kebeles. The analysis included all ve kebeles, with sample households drawn proportionally from each kebele ( Table 1). The household size determined by the following formula Yamane (1967) approach Hence, n = Sample; N = Population; e = Error term (5%) On the other hand, focus group discussions (FGD) participants were chosen based on their kebele's representatives. Furthermore, farmers were chosen for interviews based on their living and working experience in wetland areas, as well as their expertise in this eld. The information used to choose the three farmers who were interviewed was given by a developing agent who was working with them.
Questionnaires, interviews, focus group discussions (FGDs), and eld observations were used to gather data for this report. Furthermore, data was gathered from secondary sources such as Landsat images, SWAT input data (climate data such as rainfall, temperature, wind speed, relative humidity, and DEM (digital elevation model) soil map (USGS.gov) shape le, water ow data (MoW), and normalized difference vegetation index (NDVI) data (MODIS from https://doi.org/10.5067/ASTER/ASTGTM.003). Moreover, additional data were collected to see the hydrological alteration of the area, and then water ows data taken from the Ethiopian Ministry of Water. Other documents were also collected from different o ces (published and unpublished), articles from journals.
Questionnaire socio-economic data (for example, grazing land, grazing systems, land for rice production, farmland scale, recession farming, crop type, inputs, and crop yield in various years, agricultural activities such as recession farming). Besides, data was gathered from experts in the agriculture o ce at various levels using a questionnaire.

Interview
The state of wetland resource use and management, as well as the loss and bene t of wetland resources as a result of rice price uctuations. Ethio-wetland and Natural Resource Management Association were also interviewed about support and other activities related to wetlands in the Fogera oodplain.
FGD data about land use, the driving cause of land-use change, wetland resources, presence and absence of the wetland resources (plants), and wetland big animals were collected.

Field observation and GPS
Field observations were made to collect data about the land use of the study area using the checklist. GPS was also used to collect data to do ground veri cation to generate NDVI data.

Methods of data analysis
Data that were collected via questionnaires were summarized through tables, graphs, and charts. These data were analyzed through percentage, mean, and correlation. Correlations were used for water ow in m3/s, Nitrogen (N) ow in m3/s, and Phosphorous (P) ow in m3/s. Moreover, correlation and regression were employed for the stream ow out m3/s, No3 ow out and P ow out to predict the variables that indicate water pollution Indicators of Hydrological Alteration (IHA) were also generated through the software IHA Version 7. Where NIR is the datum in the near-infrared and Red is in the red area. The maps were represented using the color scale, where the lowest NDVI was associated with black, gradually changing to gray and white, the latter with values closer to 1 (González-Betancourt 2018).

Spatial and Temporal Trends in Crops Production Pattern in the area
As shown in Table 2, the spatial and temporal patterns in the area's crop production pattern are shown based on three classes, with the main emphasis on identifying the rice crop's condition. When the time series is explored in the google earth engine, the rice crop was indicated in increasing trends whereas dense vegetation, water, and other small vegetation are showing in a decreasing trend based on the calculated results of the NDVI of rice crop, vegetation, water, and others in the year 2000, 2009 and 2018 ( Fig. 2 and Table 2). The graph also clearly indicated the increasing and decreasing trends of classes. The negative slope expresses the decreasing trend while the positive slope indicates the increasing trend. Accordingly, it is indicated in Table 3, the sampled respondent mentioned that the size of their farmland before the introduction of rice was 159.75 ha but after the introduction of rice this number ipped to 284.75 ha. The difference is 125 ha.  Table 4 showed that about 88% of sampled respondent farmers responded they do have su cient farmland to produce more rice crops to satisfy their family's needs and for sale. On the other hand, about 12% of the respondents said that they have su cient farmland to produce rice only to satisfy their family needs. Respondents were asked about their previous production style before the introduction of rice and they reported that they produced different crops in the study areas. These were Teff (Eragrostis tef), maize (Zea mays L.), noug (Guizotia abyssinica), nger millet (Eleusine coracana), chickpea (Cicerarietinum), lentil (Lens culinaris), grass pea (Lathyrus sativus), green pepper (Capsicum spp.) and Barely (Hordeum Vulgare) in small amount and animal rearing at a large extent. The respondents were explained that these crops were also produced far away from the wetlands in the study site.
This time most of the respondents have been engaged in rice production during the summer season while in the winter season, they started to produce horticultural crops of vegetables like an onion (Allium cepa), garlic (Allium sativum), and tomatoes (Solanum Lycopersicum). They are grown under smallscale irrigation.
Cultivated area and crop yield produced for the year 2014 and 2015 cropping season Regarding the area cultivated for the wetlands of Fogera oodplain, the two years data showed that cultivated area coverage of the rice crop was 245.25 ha and 284.75 ha in the year 2014 and 2015, respectively (Table 5). It is also mapped that in Fig. 4, the land-use coverage for rice and other land use for the year 2013, 2015, and 2016, the result revealed the coverage for rice has shown increment. Practice on cropping pattern About 89% of the sampled household respondents reported that the types of cropping pattern practiced are mono-cropping whereas about 11% of sampled respondents said that they practiced crop rotation ( Table 6). The later respondents who pracice crop rotation explained their reason why they practiced it? This is because their farmland is far away from the oodplain which is located on the upland side of the Fogera oodplain. Past and present use of inputs to produce rice and other crops The respondent farmers were asked about the methods to maximize yield. The entire respondent responded that the methods to maximize yield are applying arti cial inputs such as fertilizer, improved seed, insecticide, and herbicide (Table 7). Furthermore, the other methods are the expansion of rice farming through encroaching wetlands and communal grazing lands. Most of the sampled household farmers said that application of insecticide has been used for most crops of chickpea (Cicer arietinum) and grass pea (Lathyrus sativus) sowed after the harvest of rice (Oryza sativa) crop. The sampled respondents were asked regarding the inputs used for other crops in the previous time. They reported that all respondents were not used arti cial input rather they used manure for the production of maize (Zea mays L.) and green pepper (Capsicum spp.). Besides, a fallowing system without any inputs was used. As it is reported in the FGD and interview, the main reasons were the population was very small in number, rice and other arti cial inputs were not introduced and adapted. It is also explained in the discussion, in previous times their farmlands were better fertile than the current one. Besides, it is reported by sampled household the cause for the reduction of yield in the study area was the reduction of soil fertility and upland erosion that brought sand and other unfertile soil particles like gravel, which reduce the amount of water in the wetland of study area. Hence, in the study area, it has been started to use arti cial input for their farmland to yield.  Fig. 5, about 45.5% of respondents already started to apply fertilizer, 23% of the respondents started to use improved seed and 77% of sampled households still use local seed. About 95% of the sampled household respondents said that they used pesticides when pests occurred in their area (eg. See photo showed in Fig. 6). This spraying of pesticides could kill insects and those insects would be eaten by birds. So, the birds could be affected. Herbicides are used to control weeds in their farmland by about 64% of the respondents.
3.2.1 Bene ts recognized from using arti cial inputs Figure 6 Spraying of pesticide in the wetland areas As Table 8 showed, almost 100% of sampled household respondents responded that the bene ts recognized from using arti cial inputs were increased yield of rice. They also said that the amount of hays getting after trashed of the crops for livestock feed was very good. Recognition of the negative impacts of arti cial inputs used As Table 9 showed that about (74.3%) household respondents reported arti cial inputs has brought water pollution (from their physical observation point of view), while about (72.5%), (96.1%), (73.2%) and (72.7%) reported that there was a reduction of the number of birds, bee's colony, sh availability in the wetlands and the Lake Tana, and other insects like reptiles, amphibians in the wetlands of the study area.  Table 10, about 22% of the sampled household respondent farmers said that they practice recession farming. That means when the water of wetland and Lake retreated (Fig. 7). This 22% of respondents also explained their experience in producing maize in the surrounding wetlands and Lake Tana when the amount of water retreats in the dry season after harvesting their rice crop. Whereas, about 78% of the sampled households were not using recession farming because their farm areas are not close to the wetlands and Lake Tana. Impacts of recession farming Respondents were also asked about the impacts of recession farming on wetland and Lake resources. According to their physical observation, 100% of respondents said that the wetland and Lake resources are reduced through time because of recession farming activities in the study area, especially papyrus, grass, birds, amount of water, the color of water, increase siltation, turbidity of the water, etc. Hence, farmers were trying to maximize their productivity through the expansion of recession farming at the expense of wetlands and Lake Tana in the study area.
The respondent farmers interviewed and FGD participants were also asked for triangulation about what changes have been observed in wetlands and water resources in their kebele. According to their response in physical observation, their explanations summarized that there was a reduction of water level in the wetland, sh, loss of papyrus and other different grass species, drying of wetland, hippopotamus in number, birds, different insects in the wetlands, etc.
The resources of wetlands reduced over time has been ranked by respondents, As Table 11 illustrated below, respondent farmers were asked to respond regarding the natural resource reduction around the wetland of Fogera. The questionnaire has different multiple choices such as the situation of the following resources like papyrus, sh, sand, birds, grass, amount of water, and hippopotamus. According to their observation, the respondent farmers tried to put the reduction of wetland resources in order of rank (Table 11). Based on the respondents' choice summary, the whole sampled respondents (385) said that papyrus has reduced rst and the others, such as sh, grass, amount of water, birds, hippocampus and sand reduction have been presented 2nd, 3rd, 4th, 5th, 6th and 7th ranked respectively (Table 11). These weighted ranks indicated us papyrus is the rst highly reduced resource and sand is the least reduced resource. Wetland conservation issues of Fogera Sampled household respondents were asked to answer regarding the wetland conservation issues. About 100% of sampled household respondents responded that they strongly want to conserve the wetlands of Fogera in the study area and the surrounding of Lake Tana. They reported that the bene ts of the conservation of wetland of Fogera can save the resources mentioned such as papyrus, sh, birds, grass, getting pure water, moderate climate, reduction of ooding, increasing soil fertility, high amount of water, increase vegetation, Provide hatchery and nursery areas for the sh, erosion control, nutrient retention, groundwater recharge, recreational activities, Habitat for hundreds of species of animals and birds, the rst line of defense against pollution from surface water runoff, increasing different insects like bees, etc. Generally, the biodiversity of the wetlands would increase. From these resources, the local people can wisely extract and use the previous style of the community.
The respondents also explained the demerit of conservation of wetlands, the whole respondents said that even though the merits of the conservation of the wetland and the Lake resources have been better, there was also the demerits of conservation of wetland summarized as the following: no use of wetlands as they want especially illegal expansion of rice agriculture to the wetlands. Recession farming is considered as a disadvantage for certain users of recession farming because they said that increasing the number of hippopotamus and birds could damage their crops, there would no freely sh harvest in the wetlands and the Lake (Fig. 8), there would not be free grazing that some of the people consider as a demerit.
The sampled household farmers, interviewed respondents and FGD participants were asked regarding the practice that was implemented in their oodplain in the study kebeles before the introduction of rice, their explanation was summarized as follows: most of the oodplain was used for grazing purpose for Fogera known indigenous cattle breed, the wetland areas were covered by papyrus vegetation, which was used for different purpose such as for roof thatching, for making of the mat, for the home fence, for making traditional shing traps for shing locally and boat making for local transportation, use of leaf of papyrus during the ceremony, Grass for roof thatching, Fishing site, some types of crops like noug, Green pepper, and nger millet, "Senele" (Butia Capitata) used for making a mat, raincoat, hut used as a cover for the dead person during his time of burial, Reeds used for making rope, brooms (Cleaning materials used a brush indicated in the left) (Fig. 9).
The sampled respondent household farmers were asked regarding their observation whether there was a signi cant land-use change observed in wetland areas. The entire sampled respondent household farmers were responded that yes, there was a signi cant land-use change in the study sample kebeles. The interviewed farmers and FGD participants have also supported their ideas.
The main reasons explained for the change observed were scarcity of agricultural land especially the introduction of rice crop encouraged the local people looking for additional farmlands to produce more rice, population growth, the tragedy of the commons (the wetland areas and the borders of Lake Tana were common resources that everyone can access with no controlling mechanism) and expansion of recession farming around the wetland areas, grazing lands, and Lake Tana to produce maize, tomato, onion, teff, etc. Therefore, according to their explanation, most of the wetland, grazing land, and forest land changed into agricultural land-use systems. These ideas have been substantiated by land use land cover change detection through Landsat image classi cation of 1973 and 2014 that showed most of the different land-use systems changed and incorporated into agricultural land-use systems.
Sampled household farmers were also asked regarding the effects of land-use changes to the wetland and Lake Tana resources to say yes or no. The whole sampled household farmer respondents said yes and this changing of the land-use system has brought the reduction of wetland and lake resources. The reduction of those wetland and lake resources has brought the consequences of negative impacts on the wetlands and Lake Tana. The negative impacts explained not only by the sampled household respondents but also by the interviewed and FGD participants explained that the seasonal over ow water, reduction of the number of resources like birds (loss of recreation and aesthetic situation of the area), loss of papyrus vegetation, the turbidity of the wetland and Lake water (physical color change observed), siltation problem and loss of reeds has been observed in the study site according to their explanation. These problems have been increasing over time in the study site.
3.3. Hydrological Alteration of the area and its driving force As Fig. 10 illustrated, the annual rainfall taken from the surrounding meteorology station and the areal rainfall of the study site has a similar pattern. Yearly average water ow and rainfall of the study site have also shown an increasing trend with positive slope values y = 0.0093x + 3.3638, R² = 0.0659 and y = 0.0093x + 3.3638 R² = 0.0762 respectively (Fig. 11). As indicated in 35 years ow average generated through (IHA) for the study area, seasonal variation of the average ow has observed (Fig. 12). This is because the season from September-July is a rainy time in the area and the season from December-October gets some rainfall in addition to that the rivers are not dry and have a good ow. Generally, looking the variability of annual water ow is due to seasonal variation of rainfall in the area. Figure 13 has also illustrated that there are similar patterns of water ow, No3, and Phosphorus in the study site.
As Table 12 illustrated summary statistics for the correlation of water ow, Nitrogen, and Phosphorous, the mean and standard deviation of water ow is 31.276 and 6.134 respectively. This is greater than the mean and standard deviation of Nitrogen (N) and Phosphorous (P). In the Pearson correlation matrix, the value of water ow in m3/s with N in m 3 /s and P in m 3 /s is -0.069 and − 0.072 respectively. These have negative relationships whereas the correlation between N in m3/s and P in m3/s has a positive correlation with the value 0.242 (Table 13). The image of the correlation matrix indicates clearly that the negative and positive correlation of each variables (Fig. 13).
The correlation graph below also supports the correlation matrix image above (Fig. 13). The correlation matrix graphs have also illustrated that how the relationship of variables ( ow in m 3 /s, N in m 3 /s and P in m 3 /s) interacted negatively and positively (Fig. 14).  (Fig. 5). According to IPMS (2005), the rice production area had increased, and farmers in seasonally ooded areas wanted to increase their rice acreage and production because the price of rice had tripled, further stimulating interest in rice production.

Practice on cropping pattern
Mono cropping is the most common cropping pattern recorded by the majority of household respondents in the study wetland areas. This result is consistent with the ndings of (Tilahun et al., 2012). We found that the introduction of rice has changed the production system, especially in the wetlands of the Fogera oodplain, from livestock-dominated to rice-dominated over the last century.

Past and present use of inputs
Before the introduction of rice, both respondents said they used manure instead of arti cial input to grow maize (Zea mays L.) and green pepper (Capsicum spp.). According to the FGD and interview session, the key factors were that arti cial inputs were unknown and the soil was extremely fertile. Previously, no organic fertilizer was used by farmers (Tegegne and Mathias 2019). Currently, he explained that all farmers apply nitrogen-based fertilizer and up to 65% of the farmers apply phosphorus-based fertilizer. Fertilizer is applied to the rice eld at different stages of growth either two or three times depending on the availability of fertilizer in the district. They use both DAP and UREA (Tegegne and Mathias 2019). Their farmlands were more fertile in the past than they are now, according to FGD participants. Furthermore, soil fertility depletion and upland erosion added sand and other unfertile soil particles, such as gravel, to the study area's wetland, decreasing the amount of water in the wetland. As a result, farmers in the study region have begun to use arti cial inputs (fertilizer, improved crop, insecticide, and herbicide) on their farmland to increase productivity. They use DAP as well as UREA (Tegegne and Mathias 2019). As a result, the biodiversity of the Fogera oodplain wetlands has decreased. For example, before the use of arti cial fertilizers, moist grasslands and herbaceous fens in Europe were used for grazing and hay-making. Rice has historically been grown in heavily transformed environments with rice paddies and a humancontrolled water regime in other parts of the world. Rice cultivation allowed for a landscape rich in diversity, particularly in macroinvertebrates, sh, and waterfowl, until the early twentieth century (Kawano 2000; Shimoda 2007). However, as a result of the intensi cation of agricultural practices associated with the 'green revolution in the second half of the twentieth century, fertilizer and pesticide use has skyrocketed, resulting in a drastic rise in pesticide and fertilizer use. Summarizing, intensive agricultural use of wetlands has changed their ecological character signi cantly, as crop growth and livestock raising necessitate reclamation initiatives. Biodiversity has also been signi cantly impacted in such wetland areas, and signi cant portions can no longer qualify as wetlands.
However, since low-intensity cultivation occurs in wetlands, requiring a regime of extensive use without fertilizers or pesticides, the landscape diversity of the wetland environment can be high, although the species composition and setting vary signi cantly from that of its natural state. Many of the species have been destroyed out by the agricultural intensi cation of the twentieth century, which included the use of fertilizers and pesticides (Millennium Ecosystem Assessment 2005).

Arti cial Inputs Used
Farmers have already begun to use arti cial inputs such as fertilizer, improved crop, pesticides, and herbicides, according to the sampled respondents. This is supported by the ndings of (IPMS 2005), which found that improving agronomic practices increased rice yields (weed control, use of fertilizers and pest and disease control). Farmers reported increased use of modern agricultural technologies such as higher-quality seed of preferred varieties, agro-chemicals (chemical fertilizer, herbicides, and pesticides), and irrigation technologies (water wells and water pumps) among other items. As a result, yields per unit of land and labor have risen. However, there have been reports that increased production is reducing soil fertility, forcing many farmers to increase their use of urea and other chemical fertilizers in order to sustain their yields.
According to a survey, no fertilizer has been applied to rice production in the district so far. Farmers, on the other hand, have started applying fertilizer in recent years as yields on their plots have declined (Hagos et al., 2014). Despite the fact that no fertilizer was used ten years ago, all farmers now use fertilizer, according to this report. Disease and pest infestation have reduced yield production, necessitating a signi cant change in fertilizer application. Fertilizer problems such as cost and availability are a source of dissatisfaction for farmers (Tegegne and Mathias 2012).
Bene ts recognized from using arti cial inputs Arti cial inputs, according to respondents, resulted in higher rice crop yields. Besides, the hay provided after the rice crops were trashed was suitable for livestock feed. According to some evidence, chemically-based agriculture produces higher yields per area than "organic" traditional practices. However, this comes at a cost: high costs due to chemical and fuel inputs (Pimentel 2005), as well as numerous environmental effects that can be detrimental in the long run (Pimentelh 1996).

Recognition of the negative impacts of arti cial inputs used
Arti cial inputs, according to the respondents' observation point of view, have resulted in water contamination, a decrease in the number of birds, bee colonies, sh availability in the wetlands and Lake Tana, and other insects such as reptiles and amphibians in the study area's wetlands. Crop yields have increased as a result of the Green Revolution's major improvements in rice cultivation, but rice cultivation has become less sustainable as a result of eutrophication, sh kills caused by pesticide toxic effects, and biodiversity loss (Bambaradeniya, 2003). Rice eld ecosystems rich in biodiversity exist in almost all rice-growing regions, according to Shimoda (2007), especially in areas where rice-growing intensi cation is impractical or impossible. Traditional rice systems were su ciently multifaceted ecosystems that did not involve the use of chemical fertilizers and maintained a moderate but stable yield for thousands of years because a diverse array of microorganisms and other invertebrates allowed them to maintain soil fertility by recycling nutrients for rice cultivation, in contrast to modern rice cultivation (Moorman and Breeman, 1978;Roger et al., 1991). Despite being ooded during the growing season, rice elds do not provide wetland habitat for wildlife or macroinvertebrates, as well as many other wetland ecosystem services including carbon sequestration and biodiversity protection (Stenert et al., 2009).
are planted, planting techniques are used, and the combination of other ood-related sources of income ( shery, for example) and strategies for coping with the risks are used differently across Ethiopia. The major regions where ood recession agriculture is considered to be practiced are Lake Tana, Baro-Akoba, Omo Valley, Wabi Shebelle, and Upper Awash. During the dry season, there are also a few small wetland areas where vegetables and other crops are grown on the drier parts. In the north of Ethiopia, ood-based farming is practiced along the shores of Lake Tana and along some of the tributaries that feed the lake. The Fogera oodplain, east of Lake Tana, revealed that the ood-prone area subject to ood recession farming year to year. The key anthropogenic problems are recession agriculture, unplanned urbanization, rapid population growth, indiscriminate manufacturing and construction activities, disposal of domestic and industrial hazardous wastes, and free grazing. Many people in the lake subbasin already consider wetlands to be unsafe breeding grounds for disease vectors. The ecological and socio-economic values of activities near Lake Wetland destruction and conversion for recession are seldom considered. Traditional wetland rice farming has proven to be highly competitive in terms of yield sustainability and wetlands fauna and ora preservation. Moderate but steady yields have been sustained for thousands of years with no negative effects on the climate.

Hydrological Alteration
Seasonal and annual variations in the hydrological functions of the study wetlands were observed. The study of wetland water ow and rainfall patterns are both similar. In the study region, there is a strong association between water ow and rainfall (r = .868**, N = 35 at P < .000). In river ecosystems, hydrological regimes create biotic diversity, and hydrological variation is recognized as a primary driving force (Taylor et al., 2003). When humans alter the ow regime, the normal cycle of hydrologic variation and ecosystem dynamics is disturbed (Dunne and Leopold 1978; Poff et al., 1997).

Conclusion
Wetlands are the ultimate groundwater recharge areas because they not only absorb rainwater and make it usable for percolation, but they also play an important role in water puri cation, nutrient preservation, ood prevention, and erosion control. As a consequence, they're also known as "landscape kidneys." Changes in wetland hydrology can affect soil chemistry as well as the plant and animal population in wetlands. Altering the natural amount of water entering a wetland or the cycle of saturation and inundation will cause the environment to shift from a wetland to another.
They have high biodiversity and are connected to the food and water protection of the region. The ndings of this study indicate that the spatial and temporal trends in crop production patterns in the area have increased because of the rice crop introduction in the Fogera oodplain. This introduction and expansion of rice farming in the study area were at the expense of wetland and grazing land losses. These indicated as there is an extended rice farming practice through recession farming. Moreover, farmers in the study area have also tried to maximize their rice yield with its intensi cation. Hence, for the intensi cation purpose farmers were used arti cial inputs which were not used before the introduction of rice crop in the area. These arti cial inputs like fertilizer, pesticides, insecticides, and herbicides have an impact on water pollution and soil degradation. These inorganic chemicals can also affect the aquatic ecosystems of the wetlands and lake. Generally, these extended and intensi cation of farming practices have an impact on the biodiversity of fauna and ora of the area.
Moreover, these anthropogenic problems coupled with rainfall variability could be a cause for hydrological alteration of the study area.  Rice verse other land use in Fogera oodplain Note: The designations employed and the presentation of the material on this map do not imply the expression of any opinion whatsoever on the part of Research Square concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. This map has been provided by the authors. Recession farming near Lake Tana and wetlands  Cleaning material, sh trap and sh with sherman (from left to right) Figure 10 Annual rainfall of the study site Figure 11 Yearly average water ow and rainfall of the study site Figure 12 35 years ow average generated through (IHA) for the study area.

Figure 13
The patterns of Flow, No3 and Phosphorus Figure 14 Image of the correlation matrix: Where, Var1 = Flow in m3/s, Var2 = N in m3/s and Var3 = P in m3/s Figure 15 Correlation matrix graph