Poolad Karimi

Producing more food with less water in a changing world: assessment of water productivity in 10 major river basins

This article summarizes the results of water productivity assessment in 10 river basins across Asia, Africa and South America, representing a range of agro-climatic and socio-economic conditions. Intensive farming in the Asian basins gives much greater agricultural outputs and higher water productivity. Largely subsistence agriculture in Africa has significantly lower water productivity. There is very high intra-basin variability, which is attributed mainly to lack of inputs, and poor water and crop management. Closing gaps between “bright spots” and the poorly performing areas are the major tasks for better food security and improved livelihoods, which have to be balanced with environmental sustainability.

Mapping basin-level water productivity using remote sensing and secondary data in the Karkheh River Basin, Iran

This article deals with water productivity (WP) assessment at a range of spatial scales for the Karkheh Basin, Iran. Sub-catchment to basin-scale estimates are based on an innovative method that uses readily available satellite images and routine secondary data. The farm-scale results are derived from the field survey of 298 farmers. The results show large variations in the WP, which indicate considerable scope for improvement. Inclusion of livestock changes both the magnitude and patterns of overall WP at the sub-catchment scale. This stresses the need for holistic accounting of all agricultural enterprises in water (re)allocation policies.

Can global precipitation datasets benefit the estimation of the area to be cropped in irrigated agriculture

The area to be cropped in irrigation districts needs to be planned according to the available water resources to avoid agricultural production loss. However, the period of record of local hydro-meteorological data may be short, leading to an incomplete understanding of climate variability and consequent uncertainty in estimating surface water availability for irrigation area planning. In this study we assess the benefit of using global precipitation datasets to improve surface water availability estimates. A reference area that can be irrigated is established using a complete record of thirty years of observed 15 river discharge data. Areas are then determined using simulated river discharges from six local hydrological models forced with in-situ and global precipitation datasets (CHIRPS and MSWEP), each calibrated independently with a sample of five years extracted from the full thirty year record. The utility of establishing the irrigated area based on simulated river discharge simulations is compared against the reference area through a pooled Relative Utility Value. Results show that for all river discharge simulations the benefit of choosing the irrigated area based on the thirty years simulated data is higher compared to 20 using only five years observed discharge data, as the statistical spread of PRUV using thirty years is smaller. Hence, it is more beneficial to calibrate a hydrological model using five years of observed river discharge and then extending it with global precipitation data of thirty years as this weighs up against the model uncertainty of the model calibration.