The response of the hydrological system in India to climate change

The INDICE project investigated the effect of climate change on the contribution of the cryosphere - glaciers and snow - to rivers in the western Himalaya region of India. The subsequent effect that these changes are having on water resource availability was also studied. By using different models to understand these changes, the project was able to investigate past and future changes affecting water resources and the effect on the local population that these changes could have in the next few years. Millions of people live in the western Himalaya region of India and are directly affected by changes in the cryosphere. Surveys were made and meetings held with representative groups so they could describe the different changes that they have observed. There are changes in precipitation - the rain is less predictable and doesn't come when it's expected and at a crucial time for planting crops, but then comes when it's not expected and causes problems. An extreme example of this occurred during the project period in September 2014, when flash floods occurred in Kashmir and nearby regions during the last stage of the monsoon season causing widespread flooding and the deaths of hundreds of people. In order to quantify the observed changes, an extensive study was made of past meteorological records. However, this proved to be a challenge as data are scarce, there are many gaps in the data series and even obtaining existing data was difficult. There are good quality data for the period 1901-1970, but after 1971 data quality is sparse and inconsistent. Hence an important and significant part of the project was to acquire the data, and then to correct gaps and anomalies in the data in order to perform the analyses. Two very different modelling methods were used to examine the data and model future changes. Why two different models? It is not advisable to rely on only one model simulation, even if the model is perfect, as natural variations are associated with non-linear processes that can?t be predicted. Empirical Statistical Downscaling (ESD) and Regional Climate Modelling (RCM) are the two methods used in this study. They use different sources of information and are based on different principles, hence they have different strengths and weaknesses. ESD is cheap in terms of computer demands and is a good method to use for downscaling large ensembles. The RCM was performed using an atmosphere model (WRF - Weather Research and Forecasting model) for the CORDEX South Asia domain to force the hydrological model (spatially distributed version of HBV model), which included an elevation interval parameterisation of glaciers and glacier shrinking. The study areas are centred on two glaciers - Kolahoi in Jammu and Kashmir, which drains into the Lidder valley watershed and Chhota Shigri in Himachal Pradesh, which drains into the Chenab watershed. The winter climate is governed by the Western Disturbance with summer precipitation from the SW monsoon, although Chhota Shigri is in the monsoon-arid transition zone. INDICE has supported the mass balance measurements of Chhota Shigri glacier over the project period, which now has the longest mass balance series in the Hindu Kush Himalaya region, with a continuous series from 2002. The average mass balance for Chhota Shigri between 2002 and 2014 was -0.56 m w.e. (water equivalent) but in some years the mass balance was positive. The mass balance calculated by the glaciological method, a total of -4.21 m w.e. between 2005 and 2014, compares well with that calculated by the geodetic method, -3.54 m w.e. This negative trend is consistent with observations from other Himalayas glaciers. The precipitation for this region has two peaks - a moderate peak during winter months and a higher peak during the monsoon. Rainfall over the Himalayan region is not consistent with the rest of India. Model results show that future rainfall will decrease by 10-25% by the end of the 21st century at most meteorological stations. The winter temperature will increase by 0.3 to 7.2 °C, according to which RCP is used. Surveys of the local communities show that the changes predicted by the models are already being detected. There is less water available for irrigation and livestock, which has led to more daily movement of animals that has negatively affected growth rates. Farmers are switching away from traditional crops such as rice to other crops. As well as the effects on agriculture and fishing, which involve a large proportion of the local communities, hydropower is also affected by decreased runoff with less water in summer when electricity is most needed for cooling. The livelihood impact assessment shows that the population in these two areas is vulnerable to the changes predicted by the models. The INDICE project worked with local and national authorities to convey the results of the project, such that they can understand the changes and decide best how to respond.

The cryospheric contribution to rivers in western Himalaya plays a significant role in water resource availability. Changes in climate in these regions lead to a significant impact on the socio-economic status of the local community in western Himalaya, a nd probably also to those at greater distances, but the magnitude and reaction time of these changes are poorly understood. There is a need to understand the physical processes behind these impacts and the socio-economic impact assessment in the region. T he work proposed in INDICE addresses these needs. The work is structured into four main themes (work packages). The first theme is the detection of feedback mechanisms from glacier ice mass balance and geometry to the atmosphere in Indian catchments in th e Himalaya region (WP1). The results from this will then provide one hydrological projection available for analyses and will establish climate projections for the region based on empirical statistical downscaling and advanced statistical analyses to impro ve our understanding of climate change signals in the region (WP2). Assessment of the mass balance and energy balance of two selected glaciers and the effect of the mass balance on river discharge is the next theme (WP3), and this also provides data to ot her work packages. WP4 includes development of a socioeconomic impact assessment based on demographic characteristics; livelihood and production systems and land use systems and will use output data from workpackages 1 to 3. Project management, organisati on and co-operation are contained in a separate work package (WP0). This includes co-ordinating the dissemination of project results. The dissemination includes two workshops for the Indian and Norwegian partners for presentation of project results. This should lead to greater incorporation of the results into local and regional policy regarding water resources. Publication of scientific results in international scientific journals will be given high priority.