A pinboard by
Ankur Dixit

Student, IIT Delhi


Water resources status and future availability

In this study we will assess the present status of water availability in Himalayan basin which is a source of fresh water for million of people down the stream. Since global warming is an established fact and has been a cause of climate change. This changing climate has affected the Asian water tower (The Great Himalaya) as well which raises major concern and necessitate to study. In this we have assessed the impact of climate change on water resource stored in form of snow and glaciers and its dynamics as well. The future projected climate used to project the future availability of water. This study can be very effective and crucial for the local policy planning. Since we have used high resolution model so local effects are captured which will eventually reflect the localized effects of the particular area. This study can be effective for planning the irrigation regulatory. This study can also be crucial in food security if coupled with agriculture problem.

So In a nutshell this study is a assessment of present status of water and an estimate in future.


The importance of aspect for modelling the hydrological response in a glacier catchment in Central Asia

Abstract: Understanding how explicit consideration of topographic information influences hydrological model performance and upscaling in glacier dominated catchments remains underexplored. In this study, the Urumqi glacier no. 1 catchment in northwest China, with 52% of the area covered by glaciers, was selected as study site. A conceptual glacier-hydrological model was developed and tested to systematically, simultaneously, and robustly reproduce the hydrograph, separate the discharge into contributions from glacier and nonglacier parts of the catchment, and establish estimates of the annual glacier mass balance, the annual equilibrium line altitude, and the daily catchment snow water equivalent. This was done by extending and adapting a recently proposed landscape-based semidistributed conceptual hydrological model (FLEX-Topo) to represent glacier and snowmelt processes. The adapted model, FLEXG, allows to explicitly account for the influence of topography, that is, elevation and aspect, on the distribution of temperature and precipitation and thus on melt dynamics. It is shown that the model can not only reproduce long-term runoff observations but also variations in glacier and snow cover. Furthermore, FLEXG was successfully transferred and up-scaled to a larger catchment exclusively by adjusting the areal proportions of elevation and aspect without the need for further calibration. This underlines the value of topographic information to meaningfully represent the dominant hydrological processes in the region and is further exacerbated by comparing the model to a model formulation that does not account for differences in aspect (FLEXG,nA) and which, in spite of satisfactorily reproducing the observed hydrograph, does not capture the influence of spatial variability of snow and ice, which as a consequence reduces model transferability. This highlights the importance of accounting for topography and landscape heterogeneity in conceptual hydrological models in mountainous and snow-, and glacier-dominated regions.

Pub.: 28 Jun '17, Pinned: 24 Aug '17

Contributions of climate change and human activities to runoff change in seven typical catchments across China.

Abstract: Climate change and human activities are two major factors affecting water resource change. It is important to understand the roles of the major factors in affecting runoff change in different basins for watershed management. Here, we investigated the trends in climate and runoff in seven typical catchments in seven basins across China from 1961 to 2014. Then we attributed the runoff change to climate change and human activities in each catchment and in three time periods (1980s, 1990s and 2000s), using the VIC model and long-term runoff observation data. During 1961-2014, temperature increased significantly, while the trends in precipitation were insignificant in most of the catchments and inconsistent among the catchments. The runoff in most of the catchments showed a decreasing trend except the Yingluoxia catchment in the northwestern China. The contributions of climate change and human activities to runoff change varied in different catchments and time periods. In the 1980s, climate change contributed more to runoff change than human activities, which was 84%, 59%, -66%, -50%, 59%, 94%, and -59% in the Nianzishan, Yingluoxia, Xiahui, Yangjiaping, Sanjiangkou, Xixian, and Changle catchment, respectively. After that, human activities had played a more essential role in runoff change. In the 1990s and 2000s, human activities contributed more to runoff change than in the 1980s. The contribution by human activities accounted for 84%, -68%, and 67% in the Yingluoxia, Xiahui, and Sanjiangkou catchment, respectively, in the 1990s; and -96%, -67%, -94%, and -142% in the Nianzishan, Yangjiaping, Xixian, and Changle catchment, respectively, in the 2000s. It is also noted that after 2000 human activities caused decrease in runoff in all catchments except the Yingluoxia. Our findings highlight that the effects of human activities, such as increase in water withdrawal, land use/cover change, operation of dams and reservoirs, should be well managed.

Pub.: 02 Jul '17, Pinned: 02 Aug '17

A Hydrologic Drying Bias in Water-Resource Impact Analyses of Anthropogenic Climate Change†

Abstract: For water-resource planning, sensitivity of freshwater availability to anthropogenic climate change (ACC) often is analyzed with “offline” hydrologic models that use precipitation and potential evapotranspiration (Ep) as inputs. Because Ep is not a climate-model output, an intermediary model of Ep must be introduced to connect the climate model to the hydrologic model. Several Ep methods are used. The suitability of each can be assessed by noting a credible Ep method for offline analyses should be able to reproduce climate models’ ACC-driven changes in actual evapotranspiration in regions and seasons of negligible water stress (Ew). We quantified this ability for seven commonly used Ep methods and for a simple proportionality with available energy (“energy-only” method). With the exception of the energy-only method, all methods tend to overestimate substantially the increase in Ep associated with ACC. In an offline hydrologic model, the Ep-change biases produce excessive increases in actual evapotranspiration (E), whether the system experiences water stress or not, and thence strong negative biases in runoff change, as compared to hydrologic fluxes in the driving climate models. The runoff biases are comparable in magnitude to the ACC-induced runoff changes themselves. These results suggest future hydrologic drying (wetting) trends likely are being systematically and substantially overestimated (underestimated) in many water-resource impact analyses.

Pub.: 26 Jun '17, Pinned: 02 Aug '17

Growth variable-specific moisture and temperature limitations in co-occurring alpine tree and shrub species, central Himalayas, Nepal

Abstract: Trees and shrubs found in the forest-tundra ecotone (FTE) are considered to be highly sensitive to climate change, but their response to climatic drivers is only partially understood. We use dendrochronological techniques to develop growth chronologies for co-occurring tree (Abies spectabilis, radial growth and height) and dwarf shrub (Cassiope fastigiata, stem elongation and leaf number) species in central Himalaya, Nepal, in order to identify and compare climate drivers of growth (temperature, precipitation, moisture (SPEI)). Our results reveal growth variable-specific responses characterized by a predominant response to previous year and non-growing season climate, and to length of the monsoon season. Tree radial growth was significantly correlated with temperature during previous summer and non-growing season months, and moisture in the late monsoon (September). Tree height increment correlated with late-monsoon temperature and moisture in the previous post-monsoon. Shrub stem elongation mainly correlated with temperature and moisture conditions in previous-year pre-monsoon (May), while leaf production correlated with moisture in previous pre-monsoon and monsoon periods, and precipitation in the late-monsoon. These results contribute new evidence that mid-latitude FTE tree and shrub species and individual growth variables are limited by unique climate drivers operational at different periods during and outside the monsoon season. Within the context of rising temperatures and increased precipitation variability in the Himalayas, moisture may become a more frequent stressor on tree and shrub growth. Consideration of climate and site variable interactions at alpine sites is important to detecting subtleties of growth response. Dendroecological studies of co-occurring tree and shrub species help to identify concomitant and disparate growth responses to climate drivers and in turn, provide information and insight into FTE changes in the Himalayas and elsewhere.

Pub.: 10 Jun '17, Pinned: 02 Aug '17

Watershed impacts of climate and land use changes depend on magnitude and land use context

Abstract: Human population growth and urban development are affecting climate, land use, and the ecosystem services provided to society, including the supply of freshwater. We investigated the effects of land use and climate change on water resources in the Yadkin–Pee Dee River Basin of North Carolina, United States. Current and projected land uses were modeled at high resolution for three watersheds representing a forested to urban land use gradient by melding the National Land Cover Dataset with data from the U.S. Forest Service Forest Inventory and Analysis. Forecasts for 2051–2060 of regional land use and climate for scenarios of low (B2) and moderately high (A1B) rates of change, coupled with multiple global circulation models (MIROC, CSIRO, and Hadley), were used to inform a distributed ecohydrological model. Our results identified increases in water yields across the study watersheds, primarily due to forecasts of increased precipitation. Climate change was a more dominant factor for future water yield relative to land use change across all land uses (forested, urban, and mixed). When land use change was high (27% of forested land use was converted to urban development), it amplified the impacts of climate change on both the magnitude and timing of water yield. Our fine-scale (30-m) distributed combined modeling approach of land use and climate change identified changes in watershed hydrology at scales relevant for management, emphasizing the need for modeling efforts that integrate the effects of biophysical (climate) and social economic (land use) changes on the projection of future water resource scenarios.

Pub.: 17 Jul '17, Pinned: 02 Aug '17

Agricultural water allocation strategies along the oasis of Tarim River in Northwest China

Abstract: Efficient reallocation of existing water supply is gaining importance as demand grows and competitions among users intensify. In extremely arid regions, where deficit irrigation needs to be applied, management decisions on agricultural water allocation are often onerous tasks due to the confliction among water users. This paper presents a hydrological modeling approach to assist decision-makers and stakeholders to resolve potential water-sharing conflicts among water users. We combine the land use map with water distribution methods to solve the water allocation problems in a large basin scale. The model is tested and applied in three steps: (i) calibration and validation of water supply and demand along the Tarim River with a combined hydrological and groundwater model, (ii) developing climate change scenarios, (iii) optimizing agricultural water allocation for the entire Tarim River Basin for these scenarios and deriving of conclusions. The comprehensive management of farmland areas and water distribution strategies are investigated in the model scenarios. The results of these assessments provide opportunities for substantial improvement on water allocation and water right. The access of a user to use the water efficiently should be guaranteed, especially in the lower reaches of the river in the arid land. In practice, the hydrological model assists on decision-making for water resource management in a large river basin, and incentive to utilize water use in an efficient manner.

Pub.: 19 Mar '17, Pinned: 02 Aug '17

Energy-water-food nexus under financial constraint environment: good, the bad, and the ugly sustainability reforms in sub-Saharan African countries.

Abstract: Environmental sustainability agenda are generally compromised by energy, water, and food production resources, while in the recent waves of global financial crisis, it mediates to increase the intensity of air pollutants, which largely affected the less developing countries due to their ease of environmental regulation policies and lack of optimal utilization of economic resources. Sub-Saharan African (SSA) countries are no exception that majorly hit by the recent global financial crisis, which affected the country's natural environment through the channel of unsustainable energy-water-food production. The study employed panel random effect model that addresses the country-specific time-invariant shocks to examine the non-linear relationship between water-energy-food resources and air pollutants in a panel of 19 selected SSA countries, for a period of 2000-2014. The results confirmed the carbon-fossil-methane environmental Kuznets curve (EKC) that turned into inverted U-shaped relationships in a panel of selected SSA countries. Food resources largely affected greenhouse gas (GHG), methane (CH4), and nitrous oxide (N2O) emissions while water resource decreases carbon dioxide (CO2), fossil fuel, and CH4 emissions in a region. Energy efficiency improves air quality indicators while industry value added increases CO2 emissions, fossil fuel energy, and GHG emissions. Global financial crisis increases the risk of climate change across countries. The study concludes that although SSA countries strive hard to take some "good" initiatives to reduce environmental degradation in a form of improved water and energy sources, however, due to lack of optimal utilization of food resources and global financial constraints, it leads to "the bad" and "the ugly" sustainability reforms in a region.

Pub.: 08 Apr '17, Pinned: 02 Aug '17