Assessing Potential Climate Change Impacts on Irrigation Requirements of Major Crops in the Brazos Headwaters Basin, Texas

Abstract

In order for the agricultural sector to be sustainable, farming practices and management strategies need to be informed by site-specific information regarding potential climate change impacts on irrigation requirements and water budget components of different crops. Such information would allow managers and producers to select cropping systems that ensure efficient use of water resources and crop productivity. The major challenge in understanding the link between cropping systems and climate change is the uncertainty of how the climate would change in the future and lack of understanding how different crops would respond to those changes. This study analyzed the potential impact of climate change on irrigation requirements of four major crops (cotton, corn, sorghum, and winter wheat) in the Brazos Headwaters Basin, Texas. The irrigation requirement of crops was calculated for the baseline period and three projected periods: 2020s (2011-2030), 2055s (2046-2065), and 2090s (2080-2099). Daily climate predictions from 15 general circulation models (GCMs) under three greenhouse gas (GHG) emission scenarios (B1, A1B, and A2) were generated for three future periods using the Long Ashton Research Station-Weather Generator (LARS-WG) statistical downscaling model. Grid-based (55 grids at~38 km resolution) irrigation water requirements (IRRs) and other water budget components of each crop were calculated using the Irrigation Management System (IManSys) model. Future period projection results show that evapotranspiration (ET) and IRR will increase for all crops, while precipitation is projected to decrease compared with the baseline period. On average, precipitation meets only 25-32% of the ET demand, depending on crop type. In general, projections from almost all GCMs show an increase in IRR for all crops for the three future periods under the three GHG emission scenarios. Irrigation requirement prediction uncertainty between GCMs was consistently greater in July and August for corn, cotton, and sorghum regardless of period and emission scenario. However, for winter wheat, greater uncertainties between GCMs were observed during April and May. Irrigation requirements show significant variations across spatial locations. There was no consistent spatial trend in changes of IRR for the four crops. A unit change in precipitation is projected to affect IRR differently depending on the crop type.

Effects of Elevated Air Temperature and CO2 on Maize Production and Water Use Efficiency under Future Climate Change Scenarios in Shaanxi Province, China

“…However, such agricultural impact assessments have not considered the effect of elevated CO 2 concentrations on maize yields under future climate changes. Furthermore, the water use efficiency and evapotranspiration will change under future climate scenarios with increasing atmospheric CO 2 concentrations [31,32]. Thus, there is a need to assess the responses of evapotranspiration and water use efficiency under future climate changes in China.…”

Estimating the Responses of Hydrological and Sedimental Processes to Future Climate Change in Watersheds with Different Landscapes in the Yellow River Basin, China

“…The LARS-WG can achieve a similar performance to other sophisticated models for site-scale temperature and precipitation estimations [28,29,30]. It is able to generate long synthetic series of daily weather data under various climate change scenarios, and can be adopted with confidence for climate change impact studies together with the watershed model for hydrological and sedimental estimations [31,32].…”

Unprecedented Drought Challenges for Texas Water Resources in a Changing Climate: What Do Researchers and Stakeholders Need to Know?

“…General guidance is available from projections of temperature, precipitation, and other such parameters (Awal et al, 2016; Modala et al, 2017), but the most valuable information would be location‐specific projections of size and variability of crop yields, given projected changes in climate means and variability and confounding factors such as insects (Deutsch et al, 2018; Steiner et al, 2017). Existing Texas projections for crop yields (Adhikari et al, 2016; Chen et al, 2019; Kothari et al, 2020) and irrigation requirements (Awal et al, 2018; Fares et al, 2017) typically consider only subset of important factors and adaptation responses, making interpretation by agriculture stakeholders challenging.…”