The sustainability of water resources mainly depends on planning and management of land use; a small change in it may affect water yield largely, as both are linked through relevant hydrological ...processes, explicitly. However, human activities, especially a significant increase in population, in-migration and accelerated socio-economic activities, are constantly modifying the land use and land cover (LULC) pattern. The impact of such changes in LULC on the hydrological regime of a basin is of widespread concern and a great challenge to the water resource engineers. While studying these impacts, the issue that prevails is the selection of a hydrological model that may be able to accommodate spatial and temporal dynamics of the basin with higher accuracy. Therefore, in the present study, the capabilities of variable infiltration capacity hydrological model to hydrologically simulate the basin under varying LULC scenarios have been investigated. For the present analysis, the Pennar River Basin, Andhra Pradesh, which falls under a water scarce region in India, has been chosen. The water balance components such as runoff potential, evapotranspiration (ET) and baseflow of Pennar Basin have been simulated under different LULC scenarios to study the impact of change on hydrological regime of a basin. Majorly, increase in built-up (13.94% approx.) and decrease in deciduous forest cover (2.44%) are the significant changes observed in the basin during the last three decades. It was found that the impact of LULC change on hydrology is balancing out at basin scale (considering the entire basin, while routing the runoff at the basin outlet). Therefore, an analysis on spatial variation in each of the water balance components considered in the study was done at grid scale. It was observed that the impact of LULC is considerable spatially at grid level, and the maximum increase of 265 mm (1985–2005) and the decrease of 48 mm (1985–1995) in runoff generation at grid were estimated. On the contrary, ET component showed the maximum increase of 400 and decrease of 570 mm under different LULC change scenario. Similarly, in the base flow parameter, an increase of 70 mm and the decrease of 100 mm were observed. It was noticed that the upper basin is showing an increasing trend in almost all hydrological components as compared to the lower basin. Based on this basin scale study, it was concluded that change in the land cover alters the hydrology; however, it needs to be studied at finer spatial scale rather than the entire basin as a whole. The information like the spatial variation in hydrological components may be very useful for local authority and decision-makers to plan mitigation strategies accordingly.
Application of satellite remote sensing in generating various geophysical parameters of land surface has gained tremendous importance in many branches of science and applied research. Out of all ...geophysical parameters of land surface derived from satellite remote sensing, the land surface temperature (LST) is of prime importance. LST acts as a governing parameter in water and energy exchange between land and atmosphere. It is an essential input to all the numerical weather prediction models, most of the process-based hydrological models and even in irrigation water management activities. Many algorithms for space-based LST retrieval and operational products of LST are available nowadays. However, these products are generally coarser in spatial and/or temporal resolutions. In the sector of irrigation water management, higher spatial resolution of all the geophysical products is prerequisites. Hence, in the present study, LST has been retrieved using two popular algorithms viz. radiative transfer theory (RTT) equation-based method and split-window (SW) algorithm. LST of Mula irrigation project command area has been retrieved using twenty images of Landsat 8 Thermal Infrared Sensor (TIRS) and Operation Land Imager (OLI) for entire Rabi/Winter season. Atmospheric parameters needed for the LST retrieval have been derived using online atmospheric correction tool. The land surface emissivity has been estimated using NDVI threshold technique. The standard daily LST product of MODIS has been used to cross-validate the LST retrieved from both the algorithms. LST retrieved using SW algorithm shows higher correlation coefficient with MODIS LST in entire command area and in agricultural land as well (0.938 and 0.925, respectively) compared to that of LST output of RTT method (0.902 and 0.894, respectively). The relative comparison of the LST products derived from RTT and SW algorithms showed that there is an average difference of ±3 °K between these two products. However, the difference is very small (−0.8 to 0.5°K) in case of agricultural area in the command. The higher correlation coefficient values between retrieved LST using both the algorithms and MODIS LST products hints toward the higher accuracy of derived LST at higher spatial resolution. These high spatial resolution LST products can further be used for irrigation water management.
AbstractIn this study, the Morgan and Duzant version of the modified Morgan-Morgan-Finney (MMF) model coupled with geographical information system (GIS) is used for sediment yield estimation from the ...Gamber watershed, Satluj basin, Himachal Pradesh, India. The model incorporates particle size selectivity in the process of erosion, transport, and deposition, i.e., it simulates these processes for clay, silt, and sand separately. This modified MMF model also allows for surface runoff and sediment routing, which improves sediment yield estimation accuracy. It also determines the watershed contributions to the total sediment yield at the basin outlet. The present research fetches the MMF model in a geospatial environment and develops a system that can be used to estimate the actual sediment yield. Generally, it has been observed that the detachment of soil is greatly affected by raindrop impact. Therefore, the estimation of kinetic energy of erosive rainfall is a very important factor. Moreover, it has been noticed that the major contribution to kinetic energy of rainfall comes from direct throughfall, as compared to leaf drainage. Therefore, the relationship to estimate kinetic energy of direct throughfall developed for Indian conditions has been used rather than the traditional relationship developed for the United Kingdom. The model parameters were calibrated for the years 1998 and 2002. The results were validated for the years 1995 and 1999. The efficiency coefficient the model could achieve was 0.91. It was concluded that the model can estimate sediment yield from a catchment with reasonable accuracy.
The spatiotemporal study of the glaciers under the changing environment is critical from the freshwater availability, especially in the perennial rivers flowing out of them during the lean season. ...The Mrigthuni Glacier, one of the major glaciers in the Pindar River basin in Uttarakhand, has been selected as a study glacier for the present analysis. The long-term (1951–2018) meteorological data analysis indicated that the temperature increased in both the maximum ablation and accumulation period; however, the precipitation decreased during the primary accumulation period. The change detected in climate patterns provided an impetus to study its impact on the glacier using geospatial techniques. It was found that the glacier front retreated by 831.4 ± 42 m at the rate of 32.94 m yr
−1
from 1990 to 2015. Further, the glacier accumulation area ratio has reduced from 55.63 to 53.22%, with a 66 m upward shift in equilibrium line altitude (ELA). The glacier's mass balance has reduced from 0.23 to 0.28 ± 0.035 m w.e. during the analysis period, based on a general equation developed for northwestern Himalaya using the optical remote sensing data. Due to the limitations of optical data, Synthetic Aperture Radar (SAR) data was used to map glacier radar zones. The distinct percolation/refreeze, transient firn, and ablation zones were identified on the SAR data composite of the different seasons. Considering SAR-based ELA as the most accurate, the analysis confirmed the negative mass balance with a value of 0.62 ± 0.036 m w.e. Therefore, it was concluded that SAR-based analysis might be vital for accurate glacier dynamics studies especially the mass balance.
In the present study, an attempt has been made to analyse the variability and trends in annual and seasonal rainfall over the Eastern Ganga Canal command area, India. To determine the trend in ...annual/seasonal rainfall and rainy days, the non‐parametric Mann−Kendall test and Sen's slope method were used over daily gridded rainfall for the time period 1901–2012. The results of the trend analysis revealed a decreasing trend in annual and monsoon rainfall in the range 18.5−61.7 and 19.4−56.7 mm/decade, respectively. For annual and monsoon rainy days, the results demonstrated a decreasing trend which varied from 1.8 to 2.9 and 1.4 to 2.2 days/decade, respectively, and an increasing trend in the range 0.2−1.4 and 1.0 days/decade, respectively. A variability analysis was performed to highlight the need for selecting an appropriate confidence level in trend analysis. It was observed that the grids showing a statistically non‐significant trend at the 95% confidence level exhibit a statistically significant trend at lower confidence levels. An analysis of dry and wet years on an annual scale revealed that the chances of occurrence of a wet year are more in comparison with the chances of occurrence of a dry year in the command area by a ratio of 14:13. However, data from the last one and a half decades has a contradictory trend with higher chances of occurrence of a dry year to very minimal chances of occurrence of a wet year. Dependable rainfall at various probability levels was estimated using a gamma distribution function. It was observed that the 75% dependable weighted annual and seasonal rainfall over the command area (985.48 and 727.54 mm) was significantly different with respect to the climatic mean weighted annual and seasonal rainfall against the weighted mean annual and seasonal rainfall (1,165.93 and 901.95 mm).
Location map of the study area with the coverage of IMD rainfall data grids.
Hydrological processes are complex to compute in hilly areas when compared to plain areas. The governing processes behind runoff generation on hillslopes are subsurface storm flow, saturation excess ...flow, overland flow, return flow and pipe storage. The simulations of the above processes in the soil matrix require detailed hillslope hydrological modelling. In the present study, a hillslope experimental plot has been designed to study the runoff generation processes on the plot scale. The setup is designed keeping in view the natural hillslope conditions prevailing in the Northwestern Himalayas, India where high intensity rainfall events occur frequently. A rainfall simulator was installed over the experimental hillslope plot to generate rainfall with an intensity of 100 mm/h, which represents the dominating rainfall intensity range in the region. Soil moisture sensors were also installed at variable depths from 100 to 1000 mm at different locations of the plot to observe the soil moisture regime. From the experimental observations it was found that once the soil is saturated, it remains at field capacity for the next 24–36 h. Such antecedent moisture conditions are most favorable for the generation of rapid stormflow from hillslopes. A dye infiltration test was performed on the undisturbed soil column to observe the macropore fraction variability over the vegetated hillslopes. The estimated macropore fractions are used as essential input for the hillslope hydrological model. The main objective of the present study was to develop and test a method for estimating runoff responses from natural rainfall over hillslopes of the Northwestern Himalayas using a portable rainfall simulator. Using the experimental data and the developed conceptual model, the overland flow and the subsurface flow through a macropore-dominated area have been estimated/analyzed. The surface and subsurface runoff estimated using the developed hillslope hydrological model compared well with the observed surface runoff for a rainfall intensity of 100 mm/h. The surface runoff hydrograph was very well predicted by the model, with correlation coefficient (R2) and Nash–Sutcliffe efficiency coefficient (E) as 0.95 and 0.91, respectively. The observed soil/macropore storage component was estimated with the help of water balance equation and compared with the model predicted macropore storage. The error in computing the soil/macropore storage was estimated as 0.38 mm i.e., 13%.
The snow and glacier melt run-off is one of the most important sources of freshwater for the perennial Himalayan rivers. The water from these rivers sustains billions of people in South Asia, ...especially during lean season. The study has been done to integrate temporal snow cover area (SCA) and digital elevation model (DEM) derived from satellite remote sensing data with Geographic Information System (GIS) and finally into temperature index-based snowmelt run-off estimation model. The study area for snowmelt run-off estimation is part of head reach sub-basins of Ganga river, i.e. Alakhnanda and Bhagirathi river basins up to Joshimath and Uttarkashi respectively. The temporal SCA (2002–07 for Bhagirathi river and 2000, 2008 for Alakhnanda river) was derived from remote sensing data and DEM was used to find elevation zones and aspect maps. Snowmelt run-off model (SRM) is a temperature index-based snowmelt run-off simulation model, which has been used in this study for simulating snowmelt run-off. The daily hydro meteorological data from India Meteorological Department and Central Water Commission were used for estimating snowmelt. Overall accuracy of SRM for Alakhnanda river in terms of coefficient of correlation (R2) is 0.84–0.90 for years 2000 and 2008, and 0.74–0.84 in Bhagirathi river for 2002–2007.
•The evaluation of HAND, TWI, and SP in a data-scarce Himalayan basin.•The reference floodplain map was simulated by MIKE11 hydrodynamic model.•HAND and TWI showed better efficacy than SP in ...floodplain mapping.•HAND showed greater consistency while TWI showed an underestimation tendency.•Integrating extensive field observations minimized the effect of DEM uncertainty.
Despite a proven record of accurate floodplain mapping, complex hydrodynamic models lack efficiency due to their data-intensive approach and high computation time. As fast-computing low-complexity alternatives, topography-based hydrogeomorphic approaches are being increasingly used in recent times. Yet, there is little evidence to suggest whether and to what extent such topography-based approaches, simply relying on Digital Elevation Models (DEMs), can effectively delineate floodplains/flood hazard zones in data-scarce, highly complex mountainous terrains. We fill this knowledge-gap by conducting a floodplain mapping comparative assessment with three topography-based approaches along a 56-km river reach in the North West Himalayas (Beas River, India). Specifically, we generated floodplain extent using Height Above the Nearest Drainage (HAND), Topographic Wetness Index (TWI), and Slope Position (SP), and estimated their relative differences compared to a reference inundation extent simulated by MIKE11 hydrodynamic model. The unique feature of our study was an extensive field survey to collect longitudinal and cross-sectional elevation data across 223 locations, which allowed us to verify vertical accuracy across multiple alternative DEMs and subsequently improve the selected DEM via bathymetry integration. Statistical measures estimating the degree of consistency across three topography-based approaches suggested that HAND and TWI produce more reasonable floodplain maps than SP. HAND-based floodplain demonstrated greater agreement with the model-simulated reference map. TWI showed moderate predictability with a tendency of underestimating floodplains. SP was largely inconsistent, demarcating floodplains in areas where the hydrodynamic model found uplands and vice versa. Our study can offer critical insights to support floodplain hydrological, biological, and habitat studies across the world’s developing countries where locally relevant delineation of floodplains remains challenging due to data scarcity.
(a) Standard false colour composite with Hyperion channels 51 (NIR-864.35nm), channel 30 (Red-650.67nm), channel 20 (Green-548.92nm). (b) Turbidity map compiled from spectral angle mapper ...classification technique with respect to turbidity using Hyperion image and field spectral library.
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•Water quality study has been done using hyperspectral remote sensing technique.•Spectral library with respect to water quality parameter developed using field spectro-radiometer.•Spectral similarity approach has been adapted for water quality mapping.•The turbidity of lake water has been analysed, which is important from inherent optical property point of view.
Turbidity is an important quality parameter of water from its optical property point of view. It varies spatio-temporally over large waterbodies and its well distributed measurement on field is tedious and time consuming. Generally, normalized difference turbidity index (NDTI), or band ratio, or regression analysis between turbidity concentration and band reflectance, approaches have been adapted to retrieve turbidity using multispectral remote sensing data. These techniques usually provide qualitative rather than quantitative estimates of turbidity. However, in the present study, spectral similarity analysis, between the spectral characteristics of spaceborne hyperspectral remote sensing data and spectral library generated on field, was carried out to quantify turbidity in the part of Chilika Lake, Odisha, India. Spatial spectral contextual image analysis, spectral angle mapper (SAM) technique was evaluated for the same. The SAM spectral matching technique has been widely used in geological application (mineral mapping), however, the application of this kind of techniques is limited in water quality studies due to non-availability of reference spectral libraries. A spectral library was generated on field for the different concentrations of turbidity using well calibrated instruments like field spectro-radiometer, turbidity meter and hand held global positioning system. The field spectra were classified into 7 classes of turbidity concentration as <5, 5–10, 10–15, 15–25, 25–45, 45–100 and >100NTU for analysis. Analysis reveal that at each location in the lake under consideration, the field spectra matched with the image spectra with SAM score of 0.8 and more. The observed turbidity at each location was also very much falling in the estimated turbidity class range. It was observed that the spectral similarity approach provides more quantitative estimate of turbidity as compared to NDTI.
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