Multi-Site Daily Rainfall Prediction for Climate Change Scenarios Using the Non-Parametric K-Nearest Neighbours

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Selection of Spatial Extent of Predictor Variables in Statistical Downscaling

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Mahanadi streamflow: climate change impact assessment and adaptive strategies

Impacts of climate change on hydrology are assessed by downscaling large scale General Circulation Model (GCM) outputs of climate variables to local scale hydrologic variables. This modeling approach is characterized by uncertainties resulting from the use of different models, different scenarios, etc. Modeling uncertainty in climate change impact assessment includes assigning weights to GCMs and scenarios, based on their performances and providing weighted mean projection for the future. This projection is further used for water resources planning and adaptation to combat the adverse impacts of climate change. The present article summarizes the recent published work of the authors on uncertainty modeling and development of adaptation strategies to climate change for the Mahanadi river in India

Characteristics of Bay of Bengal monsoon depressions in the 21st Century

We show that 21st century increase in radiative forcing does not significantly impact the frequency of South Asian summer monsoon depressions (MDs) or their trajectories in the Coupled Model Intercomparison Project Phase 5 general circulation models (GCMs). A significant relationship exists between the climatological occurrences of MDs and the strength of the background upper (lower) tropospheric meridional (zonal) winds and tropospheric moisture in the core genesis region of MDs. Likewise, there is a strong relationship between the strength of the meridional tropospheric temperature gradient in the GCMs and the trajectories of MDs over land. While monsoon dynamics progressively weakens in the future, atmospheric moisture exhibits a strong increase, limiting the impact of changes in dynamics on the frequency of MDs. Moreover, the weakening of meridional tropospheric temperature gradient in the future is substantially weaker than its inherent underestimation in the GCMs. Our results also indicate that future increases in the extreme wet events are dominated by nondepression day occurrences, which may render the monsoon extremes less predictable in the future

Is flood to drip irrigation a solution to groundwater depletion in the Indo-Gangetic plain?

Indian river basins are intensively managed with country-specific agricultural practices of cultivating submerged paddy and uncontrolled groundwater (GW) irrigation. Numerical experiments with the state-of-the-art land surface models, such as variable infiltration capacity (VIC), without incorporating region-specific practices, could be misleading. Here, we coupled VIC with 2D GW model AMBHAS, incorporating India-specific irrigation practices and crop practices, including submerged paddy fields. We performed numerical experiments to understand the causal factors of GW depletion in the northwest Indo-Gangetic plain (IGP). We identify widespread flood irrigation and cultivation of water-intensive paddy as critical drivers of the declining GW scenario. Our numerical experiments suggest that the introduction of drip irrigation reduces GW depletion in the northwest, but does not change the sign of GW level trends. The GW levels in the non-paddy fields of the middle IGP are less sensitive to irrigation practices due to the high return flow to GW for flood irrigation

Crop switching for water sustainability in India’s food bowl yields co-benefits for food security and farmers’ profits

Groundwater depletion due to agricultural intensification is a major threat to water and food security in the Indo-Gangetic Plain (IGP), a critical food bowl, home to 400 million people and currently producing 135 million metric tonnes of cereals. Among the solutions proposed to address this unsustainable water consumption, crop switching has received growing attention, yet its potential to produce co-benefits or trade-offs for other dimensions of sustainability (for example, food supply and farmers’ profits) remains largely unquantified. In this study, we developed and applied a crop switching optimization model for cereals in the IGP to maximize calorie production and farmers’ profits and minimize water consumption. We found that switching from rice to millets (pearl millet) and sorghum in the Kharif (monsoon) season and from wheat to sorghum in the Rabi (winter) season could potentially reduce water consumption by 32%, improve calorie production by 39% and increase farmers’ profits by 140%. We also found that switching crops offers a larger reduction in groundwater depletion and energy savings than improving irrigation efficiency (that is, from flood to drip irrigation). Our findings demonstrate the potential for crop switching to address the multidimensional sustainability challenges of the IGP, with possible application to other regions facing similar issues

Climate resilience of dry season cereals in India

India is the world’s second largest producer of wheat, with more than 40% increase in production since 2000. Increasing temperatures raise concerns about wheat’s sensitivity to heat. Traditionally-grown sorghum is an alternative rabi (winter season) cereal, but area under sorghum production has declined more than 20% since 2000. We examine sensitivity of wheat and sorghum yields to historical temperature and compare water requirements in districts where both cereals are cultivated. Wheat yields are sensitive to increases in maximum daily temperature in multiple stages of the growing season, while sorghum does not display the same sensitivity. Crop water requirements (mm) are 1.4 times greater for wheat than sorghum, mainly due to extension of its growing season into summer. However, water footprints (m3 per ton) are approximately 15% less for wheat due to its higher yields. Sensitivity to future climate projections, without changes in management, suggests 5% decline in wheat yields and 12% increase in water footprints by 2040, compared with 4% increase in water footprint for sorghum. On balance, sorghum provides a climate-resilient alternative to wheat for expansion in rabi cereals. However, yields need to increase to make sorghum competitive for farmer profits and efficient use of land to provide nutrients