Water Use Efficiency in Groundwater Irrigated Agricultural Plots in Semi-Arid Region: New Methodology Combining Models and In-situ Measurements.
Abstract
India is the highest user of ground water for agricultural purposes. It is difficult to conduct experimental estimation of crop water requirement for all type of crops and agricultural practices found in India. Hence, here an attempt is made to combine a hydrological model with a crop model to simulate the water requirement for semi-arid condition. We assess the potential of using the crop model calibrated for the local conditions to estimate actual and optimum water used by crops.
We used data from the experimental Berambadi watershed located in southern Karnataka, India, which is part of the Kabini Critical zone Observatory (OZCAR network http://www.ozcar-ri.org/). The average annual rainfall in the location is about 800mm and the average annual evapotranspiration is about 850mm. As the numbers suggests, ET/P is greater than 1 and the extra water requirement is met by groundwater irrigation. It resulted in declining ground water levels, failure of wells and lower crop yields. In such a scenario, to ensure farmer livelihood, it is critical to emphasise on judicious use of water. We monitored soil moisture in the root zone in a farmer plot during 3 years (2014 to 2016) using soil moisture sensors installed at two depths, 5cm and 50cm. Crop growth is monitored through LAI measurements. The crop model STICS is used for simulating crop LAI and root growth, which are used as inputs in the hydrological model Hydrus-1D which solves water movement in the vadose zone. Results show that this approach allows to simulate the dynamics of soil moisture for the different crops seasons. The estimation of water mass balance for the root zone for the 3 years show that farmers use adequate irrigation when rainfall is abundant, but they over irrigate during droughts. This suggests that there is scope for improving water use efficiency and the method proposed here can be utilized to better allocate the irrigation water to the crop during critical period.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.H13S2026U
- Keywords:
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- 1842 Irrigation;
- HYDROLOGYDE: 1880 Water management;
- HYDROLOGYDE: 6319 Institutions;
- POLICY SCIENCESDE: 6334 Regional planning;
- POLICY SCIENCES