Your search found 6 records
1 Kiptala, J. K.; Mohamed, Y.; Mul, Marloes L.; Van der Zaag, P. 2013. Mapping evapotranspiration trends using MODIS and SEBAL model in a data scarce and heterogeneous landscape in eastern Africa. Water Resources Research, 49(12):8495-8510. [doi: https://doi.org/10.1002/2013WR014240, 2013]
Mapping ; Evapotranspiration ; Evaporation ; Models ; Algorithms ; Data ; Semiarid climate ; Landscape ; Water use ; Water balance ; Water accounting ; River basins ; Land use ; Land cover ; Reservoirs ; Precipitation / Eastern Africa / Upper Pangani River Basin / Nyumba ya Mungu reservoir
(Location: IWMI HQ Call no: e-copy only Record No: H046302)
[1] Evapotranspiration (ET) accounts for a substantial amount of the water use in river basins particular in the tropics and arid regions. However, accurate estimation still remains a challenge especially in large spatially heterogeneous and data scarce areas including the Upper Pangani River Basin in Eastern Africa. Using multitemporal Moderate-resolution Imaging Spectroradiometer (MODIS) and Surface Energy Balance Algorithm of Land (SEBAL) model, 138 images were analyzed at 250 m, 8 day scales to estimate actual ET for 16 land use types for the period 2008–2010. A good agreement was attained for the SEBAL results from various validations. For open water evaporation, the estimated ET for Nyumba ya Mungu (NyM) reservoir showed a good correlations (R = 0.95; R2 = 0.91; Mean Absolute Error (MAE) and Root Means Square Error (RMSE) of less than 5%) to pan evaporation using an optimized pan coefficient of 0.81. An absolute relative error of 2% was also achieved from the mean annual water balance estimates of the reservoir. The estimated ET for various agricultural land uses indicated a consistent pattern with the seasonal variability of the crop coefficient (Kc) based on Penman-Monteith equation. In addition, ET estimates for the mountainous areas has been significantly suppressed at the higher elevations (above 2300 m a.s.l.), which is consistent with the decrease in potential evaporation. The calculated surface outflow (Qs) through a water balance analysis resulted in a bias of 12% to the observed discharge at the outlet of the river basin. The bias was within 13% uncertainty range at 95% confidence interval for Qs. SEBAL ET estimates were also compared with global ET from MODIS 16 algorithm (R = 0.74; R2 = 0.32; RMSE of 34% and MAE of 28%) and comparatively significant in variance at 95% confidence level. The interseasonal and intraseasonal ET fluxes derived have shown the level of water use for various land use types under different climate conditions. The evaporative water use in the river basin accounted for 94% to the annual precipitation for the period of study. The results have a potential for use in hydrological analysis and water accounting.
2 Wagener, T.; Franks, S.; Gupta, H. V.; Bogh, E.; Bastidas, L.; Nobre, C.; de Oliverira Galvao, C. (Eds.) 2005. Regional hydrological impacts of climatic change: impact assessment and decision making. Proceedings of the International Symposium on Regional Hydrological Impacts of Climate Variability and Change with an Emphasis on Less Developed Countries (S6) held during the 7th Scientific Assembly of the International Association of Hydrological Sciences (IAHS), Foz do Iguaco, Brazil, 3-9 April 2005. Part 1. Wallingford, UK: International Association of Hydrological Sciences (IAHS). 356p. (IAHS Publication 295)
Climate change ; Hydrological factors ; Impact assessment ; Decision making ; Agricultural development ; River basins ; Water resources ; Water management ; Coastal area ; Stream flow ; Catchment areas ; Semiarid climate ; Lakes ; Population growth ; Air pollution ; Land cover change ; Hydroelectric schemes ; Flooding ; Evapotranspiration ; Watersheds ; GIS ; Arid zones ; Semiarid zones ; Sea water ; Water temperature ; Alluvial aquifers ; Models ; Satellite observation ; Forecasting ; Afforestation ; El Nino-Southern Oscillation ; Case studies / South America / North America / Europe / Africa / Asia / Brazil / Argentina / USA / Greece / Balkan Peninsula / West Africa / Benin / Cameroon / Lebanon / Nepal / Pakistan / India / China / Western Australia / Northeast Brazil / Trinidad / Vietnam / Eastern Australia / La Plata Basin / Taquari River Basin / Patagonia / Aliakmon River Basin / Black Sea / Volta Basin / Logone-Chari Plain / Himalayan Basin / Upper Indus Basin / Ganga Basin / Damodar River Basin / Yellow River Basin / Susannah Brook / Nordeste / St. Joseph Watershed / Himalayas / Red River Basin / Indian Ocean
(Location: IWMI HQ Call no: 577.22 G000 WAG Record No: H046622)
(0.44 MB)
3 Sorensen, J. P. R.; Davies, J.; Ebrahim, Girma Y.; Lindle, J.; Marchant, B. P.; Ascott, M. J.; Bloomfield, J. P.; Cuthbert, M. O.; Holland, M.; Jensen, K. H.; Shamsudduha, M.; Villholth, Karen G.; MacDonald, A. M.; Taylor, R. G. 2021. The influence of groundwater abstraction on interpreting climate controls and extreme recharge events from well hydrographs in semi-arid South Africa. Hydrogeology Journal, 29(8):2773-2787. [doi: https://doi.org/10.1007/s10040-021-02391-3]
Groundwater extraction ; Groundwater recharge ; Well hydrographs ; Semiarid climate ; Catchment areas ; Groundwater table ; Rain ; River flow ; Stream flow ; Extreme weather events ; El Nino-Southern Oscillation ; Hydrogeology ; Boreholes ; Spatial distribution ; Land use / South Africa / Limpopo / Mogalakwena Catchment / Sand River Catchment
(Location: IWMI HQ Call no: e-copy only Record No: H050671)
https://link.springer.com/content/pdf/10.1007/s10040-021-02391-3.pdf
https://vlibrary.iwmi.org/pdf/H050671.pdf
https://vlibrary.iwmi.org/pdf/H050671.pdf
(6.26 MB) (6.26 MB)
There is a scarcity of long-term groundwater hydrographs from sub-Saharan Africa to investigate groundwater sustainability, processes and controls. This paper presents an analysis of 21 hydrographs from semi-arid South Africa. Hydrographs from 1980 to 2000 were converted to standardised groundwater level indices and rationalised into four types (C1–C4) using hierarchical cluster analysis. Mean hydrographs for each type were cross-correlated with standardised precipitation and streamflow indices. Relationships with the El Nino– Southern Oscillation (ENSO) were also investigated. The four hydrograph types show a transition of autocorrelation over increasing timescales and increasingly subdued responses to rainfall. Type C1 strongly relates to rainfall, responding in most years, whereas C4 notably responds to only a single extreme event in 2000 and has limited relationship with rainfall. Types C2, C3 and C4 have stronger statistical relationships with standardised streamflow than standardised rainfall. C3 and C4 changes are significantly (p < 0.05) correlated to the mean wet season ENSO anomaly, indicating a tendency for substantial or minimal recharge to occur during extreme negative and positive ENSO years, respectively. The range of different hydrograph types, sometimes within only a few kilometres of each other, appears to be a result of abstraction interference and cannot be confidently attributed to variations in climate or hydrogeological setting. It is possible that high groundwater abstraction near C3/C4 sites masks frequent small-scale recharge events observed at C1/C2 sites, resulting in extreme events associated with negative ENSO years being more visible in the time series.
4 Ramilan, T.; Kumar, S.; Haileslassie, Amare; Craufurd, P.; Scrimgeour, F.; Kattarkandi, B.; Whitbread, A. 2022. Quantifying farm household resilience and the implications of livelihood heterogeneity in the semi-arid tropics of India. Agriculture, 12(4):466. [doi: https://doi.org/10.3390/agriculture12040466]
Households ; Resilience ; Livelihoods ; Strategies ; Semiarid climate ; Crops ; Irrigation ; Farmers ; Multivariate analysis / India / Telangana / Maharashtra
(Location: IWMI HQ Call no: e-copy only Record No: H051087)
https://www.mdpi.com/2077-0472/12/4/466/pdf?version=1648435207
https://vlibrary.iwmi.org/pdf/H051087.pdf
https://vlibrary.iwmi.org/pdf/H051087.pdf
(1.03 MB) (1.03 MB)
The vast majority of farmers in the drylands are resource-poor smallholders, whose livelihoods depend heavily on their farming systems. Therefore, increasing the resilience of these smallholders is vital for their prosperity. This study quantified household resilience and identified livelihoods and their influence on resilience in the semiarid tropics of India by analysing 684 households. A resilience capacity index was devised based on the composition of household food and non-food expenditure, cash savings, and food and feed reserves. The index ranged from 8.4 reflecting highly resilient households with access to irrigation characteristics, to -3.7 for households with highly limited resilience and low household assets. The livelihoods were identified through multivariate analysis on selected socioeconomic and biophysical variables; households were heterogeneous in their livelihoods. Irrigated livestock and rainfed marginal types had the highest and lowest resilience capacity index with the mean score of 0.69 and -1.07, respectively. Finally, we quantified the influence of livelihood strategies on household resilience. Household resilience was strengthened by the possession of livestock, crop diversification and access to irrigation. Low resilience is predominantly caused by low household assets. The resilience capacity index and derived livelihood strategies helps to understand the complexity of household resilience, and will aid in targeting technology interventions for development.
5 Ouassissou, R.; Lacombe, G.; Kuper, M.; Hammani, A.; El Amrani, M. 2022. The role of water and energy use in expanding the boundaries of irrigated agriculture in the Berrechid Plain of Morocco. Irrigation and Drainage, 12p. (Online first) [doi: https://doi.org/10.1002/ird.2720]
Water use ; Energy consumption ; Foods ; Nexus ; Irrigated farming ; Groundwater ; Land tenure ; Semiarid climate ; Irrigation systems ; Drip irrigation ; Pumping ; Transfer of waters ; Reservoirs / Morocco / Berrechid Plain
(Location: IWMI HQ Call no: e-copy only Record No: H051180)
(1.19 MB) (1.19 MB)
Despite the attention given to the water–energy–food nexus, there is little field evidence of how this plays out for irrigators. This article analyses the diversity of irrigation system configurations and their related water and energy use in semi-arid Morocco, where groundwater-fed and pressurized drip irrigation, although supposedly thrifty, is energy intensive. The analysis relying on hydraulic calculations and multiple linear regressions was based on interviews, observations and measurements on irrigation systems in 25 farms. The results show that each farmer used between one and three pumps and up to two storage reservoirs to pump groundwater from up to 120 m deep borehole(s) and transfer it along a distance often exceeding 2 km to reach available fertile lands that are rented. Such distances had little effect on the system-wise energy consumption, varying between 4.62 and 4.88 kWh m-3, although the recycled car engines powering these irrigation systems were largely inefficient, consuming on average 2.5 kWh m-3. State subsidies encourage these water-intensive and energy-inefficient farming systems, increasing pressure on groundwater and land. These findings underline the importance of going beyond a strict nexus perspective, as expansion of the ‘groundwater economy’ is accompanied by conflicts over tenure and increasing inequalities in access to water that threaten the sustainability of irrigated agriculture.
6 Ali, A. A.; Bouchaou, L.; Er-Raki, S.; Hssaissoune, M.; Brouziyne, Youssef; Ezzahar, J.; Khabba, S.; Chakir, A.; Labbaci, A.; Chehbouni, A. 2023. Assessment of crop evapotranspiration and deep percolation in a commercial irrigated citrus orchard under semi-arid climate: combined Eddy-Covariance measurement and soil water balance-based approach. Agricultural Water Management, 275:107997. [doi: https://doi.org/10.1016/j.agwat.2022.107997]
Irrigated farming ; Citrus ; Evapotranspiration ; Deep percolation ; Semiarid climate ; Commercial farming ; Soil water balance ; Energy balance ; Agriculture ; Water management ; Irrigation management ; Irrigation scheduling ; Water supply ; Water stress ; Rain ; Crop water use ; Mediterranean climate ; Eddy covariance / Morocco / Souss-Massa
(Location: IWMI HQ Call no: e-copy only Record No: H051504)
https://www.sciencedirect.com/science/article/pii/S0378377422005443/pdfft?md5=d4f0a4edbb61d5f3f910c624caa72c48&pid=1-s2.0-S0378377422005443-main.pdf
https://vlibrary.iwmi.org/pdf/H051504.pdf
https://vlibrary.iwmi.org/pdf/H051504.pdf
(3.43 MB) (3.43 MB)
An accurate estimate of crop coefficient (Kc) values at different development stages (Kcini, Kcmid, and Kcend) is crucial for assessing crop water requirements in semi-arid regions. The objectives of this study were first to quantify the reference evapotranspiration (ETo) and to calculate the actual evapotranspiration (ETa) over citrus in a semi-arid climate under drip irrigation. For this purpose, a site of a citrus orchard in Souss-Massa, planted with the Esbal variety of clementine, was equipped with an Eddy-Covariance (EC) system, and sensors to measure radiation, soil heat flux, and micrometeorological forcing data, during 2020 and 2021 seasons. Also, the soil moisture content at various soil depths in the root zone near the EC tower was monitored. The energy balance closure (EBC) approach was adopted for flux assessment to ensure a quality check for the EC measurements. The obtained EBCs were about 82% and 79% for the daily measurements in 2020 and 2021, respectively, which can be considered acceptable considering the nature of the citrus orchard (relatively tall and sparse). Second, the study aimed to estimate actual Kc act values for citrus under the same irrigation strategy. The derived values were compared to different recommended Kc values in the literature. In the third stage, this work aimed to offer an alternative plan to sustainable irrigation management by elaborating an irrigation schedule for citrus crops in the region using the FAO-56 simple approach to avoid water stress and deep percolation (i.e., Ks = 1 and DP = 0). Eventually, an irrigation schedule was drawn following the crop’s phenological stages. The seasonal mean citrus evapotranspiration (ETa) values are 1.68, 3.02, and 1.86 mm/day for the initial, mid, and end-season. The seasonal actual Kc act values were 0.64, 0.58, and 0.64 for Kcini, Kcmid, and Kcend, respectively. Additionally, the application of the water balance equation revealed that a large quantity of water is lost through deep percolation (52% of total water supplied). The study focuses on Citrus trees being a strategic crop with important socio-economic values in the Souss-Massa region. Thus, the results should support both scientists and farmers in planning and strategy development.
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