A GIS-Based Approach to Estimate Electricity Requirements for Small-Scale Groundwater Irrigation

Access to modern energy services is a precondition to improving livelihoods and building resilience against climate change. Still, electricity reaches only about half of the population in Sub-Saharan Africa (SSA), while about 40% live under the poverty line. Heavily reliant on the agriculture sector and increasingly affected by prolonged droughts, small-scale irrigation could be instrumental for development and climate change adaptation in SSA countries. A bottom-up understanding of the demand for irrigation and associated energy services is essential for designing viable energy supply options in an effective manner. Using Uganda as a case study, the study introduces a GIS-based methodology for the estimation of groundwater irrigation requirements through which energy demand is derived. Results are generated for two scenarios: (a) a reference scenario and (b) a drought scenario. The most critical need is observed in the northern and southern regions of the country. The total annual irrigation demand is estimated to be ca. 90 thousand m3, with the highest demand observed in the months of December through February, with an average irrigation demand of 445 mm per month. The highest energy demand is observed in the northern part of the study area in January, reaching 48 kWh/ha. The average energy demand increases by 67% in the drought scenario. The study contributes to current gaps in the existing literature by providing a replicable methodological framework and data aimed at facilitating energy system planning through the consideration of location-specific characteristics at the nexus of energy–water–agriculture.

Early transplanting of rainfed rice minimizes irrigation demand by utilizing rainfall

Background Rainfall is the key contributor to provide soil moisture for wet season rice (T. Aman) cultivation. Erratic rainfall often causes water shortage resulting negative impact on plant growth and grain yield. The study aimed to determine suitable transplanting window that utilize maximum rainfall for T. Aman rice. Firstly, three years field experiment were conducted in Kushtia, Bangladesh from T. Aman, 2013 to 2015, and then the findings were implemented for another two adjacent locations, Panba and Rajshahi. The field experiment considered six transplanting dates of popular cultivar BR11 (growth duration 145 days) at 7 days interval starting from 10 July to 14 August. The CROPWAT 8.0 model was used to calculate crop water requirement (CWR), effective rainfall and irrigation demand (ID) from collected weather data in each growth phase of rice. Results In all locations T. Aman rice received enormous rainfall up to vegetative phase resulting no irrigation demand in all three tested years. The early transplanting received more rainfall in reproductive phase than late planting. Thus, Irrigation demand increased at reproductive phase with delay transplanting in moderate drought prone Kushtia, Pabna and Rajshahi. A significant relationship (R2 = 0.71) observed between reproductive phase ID and grain yield, while grain yield responded weakly with the ID at ripening phase. Based on yield performance 10–24 July found suitable transplanting window for BR11 in Kushtia. Considering the relationship between ID and grain yield, 10–17 July and 10–24 July considered the best transplanting window in Pabna and Rajshahi, respectively. Conclusions Location specific suitable transplanting windows were selected considering minimum ID at reproductive phase and the maximum grain yield. Delay in transplanting demanded more irrigation and reduced grain yield. Whereas, early transplanting utilized maximum rainfall, reduced ID in reproductive stage and ensured desired grain yield.

Early Transplanting of Rainfed Rice Minimizes Irrigation Demand by Utilizing Rainfall

BackgroundRainfall is the key contributor to provide soil moisture for wet season rice (T. Aman) cultivation. Erratic rainfall often causes water shortage resulting negative impact on plant growth and grain yield. The study aimed to determine suitable transplanting window that utilized maximum rainfall for long duration (145 days) rice cultivar. Firstly, three years field experiment conducted in Kushtia, Bangladesh in T. Aman season from 2013 to 2015, and then the findings were implemented for another two adjacent locations, Panba and Rajshahi. The field experiment considered six transplanting dates of popular cultivar BR11 at 7 days interval starting from 10 July up to 14 August. The CROPWAT 8.0 model was used to calculate crop water requirement (CWR), effective rainfall and irrigation demand (ID) from collected weather data in each growth phase of rice. A suitable transplanting window was selected considering minimum ID at reproductive phase and the maximum grain yield. ResultsT. Aman rice received enormous rainfall and accounted no irrigation at vegetative phase in all three tested years in all locations. The early transplanting received more rainfall in reproductive phase than late planting practice. Thus, Irrigation demand increased at reproductive phase with delay transplanting in moderate drought prone Kushtia, Pabna and Rajshah. A significant relationship (R2 = 0.71) observed between ID at reproductive phase to grain yield, while grain yield responded weakly with the ID at ripening phase. Based on yield performance 10-24 July found suitable transplanting window for BR11 in Kushtia. Applying ID vs yield relationship, 10-17 July and 10-24 July considered the best transplanting window in Pabna and Rajshahi, respectively. ConclusionsDelay in transplanting demanded more irrigation and reduced yield. Consequently, early transplanting utilized maximum rainfall, reduced ID in reproductive stage and ensured desired grain yield.

Estimation Of Water Requirement Of Lycopersicon Esculentum Mill

Crop water requirements of Roma tomato that planted on different spacing for four treatment and its replications in Nyagatare district Kinihira village have been computed with CROPWAT 8.0 using the meteorological parameters. The water requirement was computed using evapotranspiration (ET0), effective rainfall, Net Irrigation demand, the Gross Irrigation demand and irrigation interval for crops grown in different treatment of different spacing have been computed. Based on the rainfall data, effective rainfall and soil characteristics of the experiment site, it was shown that the total net irrigation requirement of tomato in experiment site as presented in CROPWAT 8.0 is 286.2mm and the total gross irrigation requirement is 408.8mm.The total water loss during irrigation is obtained by taking the total gross irrigation requirement minus the total net irrigation requirement and found to be122.6mm. As per CROPWAT 8.0, Tomato water requirement in whole growing stages is 620.3mm .This total water required by tomato at experimental site was supplied to crop by rainfall as effective rainfall (211.5mm) and the remaining portion (408.8mm) was supplied to crop through irrigation. A wide spectrum of scenarios has been discussed in the paper along with the guidelines for future management of water resources.

Irrigation and crop water requirement estimation for oil palms using soil moisture balance model in Peninsular Malaysia

This study presents the irrigation and crop water estimation in a Malaysian oil palm plantation for effective irrigation water management during water years 2013 and 2014. The study area was divided into four plots: 2000, 2002, 2006 and 2010, indicating years of peat swamp forest conversion to oil palm plantation. Hydrologic Engineering Centre-Hydrologic Modeling System (HEC-HMS) and Soil moisture balance hydrologic models were used to model the rainfall-runoff in the basin. Statistical analysis using coefficient of determination (R2) and Nash–Sutcliffe efficiency coefficient (NSE) were used to evaluate the performance and correlation of the two hydrologic models. The result showed that R2 and NSE were 0.94 and 0.90 respectively for calibration and 0.92 and 0.54 respectively, for monthly validation. This showed that the models performed well for simulation of the peatland hydrology. With the modelling of rainfall-runoff satisfied, the irrigation demand of the study plots was determined using the same soil moisture balance model. The irrigation demand ranged from 0.893 to 1.6 million cubic meters (MCM) in 2010 and 2000 study plots respectively. Irrigation demand is observed to be site specific which depends on the soil moisture deficit, readily available water in the oil palm root zone and oil palm rooting depth. Estimation of a future oil palm water requirement using the soil moisture balance model would be recommended for further studies for use as an advisory manual for the oil palm managers to enhance adequate water resources planning for oil palm productivity.

Assessing the Spatial Pattern of Irrigation Demand under Climate Change in Arid Area

Studying the pattern of agricultural water demand under climate change has great significance for the regional water resources management, especially in arid areas. In this study, the future pattern of the irrigation demand in Hotan Oasis in Xinjiang Uygur Autonomous Region in Northwest China, including Hotan City, Hotan County, Moyu County and Luopu County, was assessed based on the general circulation models (GCMs) and the Surface Energy Balance System model (SEBS). Six different scenarios were used based on the GCMs of BCC_CSM1.1, HadGEM2-ES and MIROC-ESM-CHEM under the Representative Concentration Pathway (RCP) 4.5 and RCP 8.5. The results showed that the method integrating the GCMs and SEBS to predict the spatial pattern was useful. The irrigation demand of Hotan Oasis will increase in 2021–2040. The annual irrigation demand of Hotan City is higher, with 923.2 and 936.2 mm/a in 2021–2030 and 2031–2040, respectively. The other three regions (Hotan County, Moyu County and Luopu County) are lower in the six scenarios. The annual irrigation demand showed a spatial pattern of high in the middle, low in the northwest and southeast under the six scenarios in 2021–2040. The study can provide useful suggestions on the water resources allocation in different regions to protect water resources security in arid areas.