Determining hydrological regimes in an agriculturally used tropical inland valley wetland in Central Uganda using soil moisture, groundwater, and digital elevation data

Gabiri, Geofrey; Diekkrüger, Bernd; Leemhuis, Constanze; Burghof, Sonja; Näschen, Kristian; Asiimwe, Immaculate; Bamutaze, Yazidhi

doi:10.1002/hyp.11417

Cited by 28 publications

(22 citation statements)

References 46 publications

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“…This development is triggered by several issues, such as increasing food demand caused by demographic growth, climate change, and degradation of upland soils. Unlike the uplands, wetlands hold potential for year-round harvest, due to their fertile soils with a balanced soil water availability throughout the year [5].…”

Section: Introductionmentioning

confidence: 99%

Hydrological Modeling in Data-Scarce Catchments: The Kilombero Floodplain in Tanzania

Näschen

Diekkrüger

Leemhuis

et al. 2018

Water

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Deterioration of upland soils, demographic growth, and climate change all lead to an increased utilization of wetlands in East Africa. This considerable pressure on wetland resources results in trade-offs between those resources and their related ecosystem services. Furthermore, relationships between catchment attributes and available wetland water resources are one of the key drivers that might lead to wetland degradation. To investigate the impacts of these developments on catchment-wetland water resources, the Soil and Water Assessment Tool (SWAT) was applied to the Kilombero Catchment in Tanzania, which is like many other East African catchments, as it is characterized by overall data scarcity. Due to the lack of recent discharge data, the model was calibrated for the period from 1958-1965 (R 2 = 0.86, NSE = 0.85, KGE = 0.93) and validated from 1966-1970 (R 2 = 0.80, NSE = 0.80, KGE = 0.89) with the sequential uncertainty fitting algorithm (SUFI-2) on a daily resolution. Results show the dependency of the wetland on baseflow contribution from the enclosing catchment, especially in dry season. Main contributions with regard to overall water yield arise from the northern mountains and the southeastern highlands, which are characterized by steep slopes and a high share of forest and savanna vegetation, respectively. Simulations of land use change effects, generated with Landsat images from the 1970s up to 2014, show severe shifts in the water balance components on the subcatchment scale due to anthropogenic activities. Sustainable management of the investigated catchment should therefore account for the catchment-wetland interaction concerning water resources, with a special emphasis on groundwater fluxes to ensure future food production as well as the preservation of the wetland ecosystem.

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Section: Introductionmentioning

confidence: 99%

Hydrological Modeling in Data-Scarce Catchments: The Kilombero Floodplain in Tanzania

Näschen

Diekkrüger

Leemhuis

et al. 2018

Water

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“…The similarity of this study to previous works is the type of data (soil moisture content, depth to groundwater level, soil physical properties, leaf area index, and climatic data) used for model calibration and simulation of soil water dynamic and vertical fluxes. Many studies have described and explained the factors that influence soil water dynamics [6,37,38] and soil moisture retention [16,39,40] at the wetland-catchment scale in East Africa. However, these studies are tailored to inland valley wetlands, yet floodplain wetlands exhibit different hydrological behavior compared to the inland valley wetlands.…”

Section: Introductionmentioning

confidence: 99%

Modeling Spatial Soil Water Dynamics in a Tropical Floodplain, East Africa

Gabiri

Burghof

Diekkrüger

et al. 2018

Water

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Analyzing the spatial and temporal distribution of soil moisture is critical for ecohydrological processes and for sustainable water management studies in wetlands. The characterization of soil moisture dynamics and its influencing factors in agriculturally used wetlands pose a challenge in data-scarce regions such as East Africa. High resolution and good-quality time series soil moisture data are rarely available and gaps are frequent due to measurement constraints and device malfunctioning. Soil water models that integrate meteorological conditions and soil water storage may significantly overcome limitations due to data gaps at a point scale. The purpose of this study was to evaluate if the Hydrus-1D model would adequately simulate soil water dynamics at different hydrological zones of a tropical floodplain in Tanzania, to determine controlling factors for wet and dry periods and to assess soil water availability. The zones of the Kilombero floodplain were segmented as riparian, middle, and fringe along a defined transect. The model was satisfactorily calibrated (coefficient of determination; R 2 = 0.54-0.92, root mean square error; RMSE = 0.02-0.11) on a plot scale using measured soil moisture content at soil depths of 10, 20, 30, and 40 cm. Satisfying statistical measures (R 2 = 0.36-0.89, RMSE = 0.03-0.13) were obtained when calibrations for one plot were validated with measured soil moisture for another plot within the same hydrological zone. Results show the transferability of the calibrated Hydrus-1D model to predict soil moisture for other plots with similar hydrological conditions. Soil water storage increased towards the riparian zone, at 262.8 mm/a while actual evapotranspiration was highest (1043.9 mm/a) at the fringe. Overbank flow, precipitation, and groundwater control soil moisture dynamics at the riparian and middle zone, while at the fringe zone, rainfall and lateral flow from mountains control soil moisture during the long rainy seasons. In the dry and short rainy seasons, rainfall, soil properties, and atmospheric demands control soil moisture dynamics at the riparian and middle zone. In addition to these factors, depths to groundwater level control soil moisture variability at the fringe zone. Our results support a better understanding of groundwater-soil water interaction, and provide references for wetland conservation and sustainable agricultural water management.

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“…These high inter-zonal differences in maize growth, biomass, and grain productivity were probably related to the variability in soil moisture and fertilizer-use efficiency along the slope of the inland valley. A related study [20] at the same experimental site showed that soil moisture was generally higher at the center of the inland valley and decreased up-slope toward the fringe position ( Figure 2). They also found that soils at the center remained saturated for a longer time following precipitation when compared to the fringe and middle positions probably due to the higher levels of silt and soil organic carbon.…”

Section: Effect Of Hydrological Positionmentioning

confidence: 81%

“…The hydrological positions/sites were separated from each other by 20 m wide strips of natural (indigenous) vegetation, which remained undisturbed throughout the duration of the experiments. In the Namulonge inland valley, loamy soils prevail, with a predominance of silty loam Gleysols [20]. Other physical soil properties varied across the hydrological positions.…”

Section: Description Of the Experimental Sitementioning

confidence: 99%

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Potential of Cultivating Dry Season Maize along a Hydrological Gradient of an Inland Valley in Uganda

et al. 2019

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Inland valley wetlands with higher soil moisture than surrounding uplands offer a yet unexplored opportunity for increasing maize production in East Africa. For three consecutive years, we conducted field experiments to assess the potential of an inland valley in Central Uganda for producing dry season maize. A randomized complete block design was used with six treatments including farmer’s practice, unfertilized control, organic and inorganic fertilizer applications at high and low rates. These were repeated four times at each of the three hydrological positions of the inland valley (fringe, middle, and center). The maize grain yield of 3.4 t ha–1 (mean across treatments and years) exceeded the national yield average by 42%. High and sustained soil moisture in the center position of the inland valley was associated with the highest grain yields irrespective of the year. Due to soil moisture deficit in the fringe and middle hydrological positions, grain yields were not only lower but also highly variable. Intensive manuring with a combination of green and poultry manure produced high yields that were comparable to those with mineral fertilizers (both at 120 kg N ha–1). Lower amounts of either mineral or organic fertilizer (60 kg N ha–1) provided no yield gain over the unfertilized control. Inland valley wetlands, thus, offer promise for farmers to harvest an additional maize crop during the dry season, thus contributing to farm income and regional food security.

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Determining hydrological regimes in an agriculturally used tropical inland valley wetland in Central Uganda using soil moisture, groundwater, and digital elevation data

Cited by 28 publications

References 46 publications

Hydrological Modeling in Data-Scarce Catchments: The Kilombero Floodplain in Tanzania

Hydrological Modeling in Data-Scarce Catchments: The Kilombero Floodplain in Tanzania

Modeling Spatial Soil Water Dynamics in a Tropical Floodplain, East Africa

Potential of Cultivating Dry Season Maize along a Hydrological Gradient of an Inland Valley in Uganda

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