Modeling the impacts of increase in temperature on irrigation water requirements in Palakkad district: a case study in humid tropical Kerala

Abstract

Rise in temperature is one of the predicted impacts of climate change with significant implications on water resources management. An attempt has been made to calculate the water requirement of crops in different agro-ecological zones of Palakkad district in humid tropical Kerala using the CROPWAT 8.0 model. Sensitivity analysis was done for a simulated rise in temperature from 0.5 to 3.0 °C keeping other parameters the same. The analysis showed that the total crop water requirement of all the major crops, like coconut, paddy and banana, increased with rising temperature thereby increasing the simulated irrigation water demand. The gross water demand inclusive of irrigation, domestic and industries will be 1,496 Mm3. The simulated gross water demand for an increase in temperature of 0.5, 1.0, 2.0 and 3.0 °C will be 1,523, 1,791, 1,822 and 1,853 Mm3, respectively. The maximum utilizable water resource available in the district is only 1,579 Mm3 and better water management, focusing particularly on improving the irrigation efficiency, has to be adopted to cater for the demands of the user sectors under changing climate scenario. A wide spectrum of climate change scenarios is also discussed in the paper along with guidelines for the future management of water resources.

FAO-CROPWAT Model-Based Estimation of Crop Water Need and Appraisal of Water Resources for Sustainable Water Resource Management:Pilot Study for Kollam District - Humid Tropical Region of Kerala, India

“…Effective rainfall: Effective rainfall is calculated based on rainfall data available from various stations within these AEUs, using the inbuilt formula (eqs (2) and (3)) of USDA Soil Conservation Service (SCS) in CROPWAT model. P eff (dec) = (P dec * (125 -0.6 * P dec ))/125 for…”

“…Details such as planting season, crop duration, depth of active root zone, canopy coverage as a percentage of spacing of various crops are based on earlier studies 2,22 . Crop coefficient values (K c ) used in our study are given in Table 2.…”

“…This data confirms that there are variations in the case of quantity of total water required for different crops within the district, and it is mainly because of the difference observed in climate parameters and existing soil types. This shows that it is indispensable to adopt scientific water management based on the need of the crop, so that higher crop yield and water productivity can be attained with optimal quantity of water, provided all other management practices are adopted 2,22,31 .…”

“…SEVERE water scarcity occurs in many countries, particularly in India, and agricultural water use is progressively becoming more limited in the light of growing water demands of various sectors 1,2 . Any realistic policy planning for crop suitability needs a comprehensive understanding of the climate, particularly rainfall (its spatial and timely availability and their variability), demand for evaporation (solar radiation, wind speed and temperature) and existing water resources.…”

Irrigation water planning for crops in the central highlands of Ethiopia, aided by FAO CROP WAT MODEL

“…Water supply matters in the world that will soon have to grow food for billions more people as world population is projected to peak at 9.3 billion in 2050, an increase of 28%. Analysis showed that the total crop water requirement of all major crops increased with the rising temperature thereby increasing the simulated irrigation water demand (Kijne, 2010;Surendran et al, 2014). In the future, food and livelihood security may be challenged due to global environmental changes, particularly global climatic changes that evidence has *Corresponding author.…”