The fundamental tools to study the budgeting of terrestrial waters are flow, spatial distribution, storage and variability of freshwater on land (Kundzewicz et al., 2007). Mountainous areas are the main hydrological triggers of the water cycle (de Jong et al., 2005).
Introduction
Overview
The fresh water on earth is less than 2.5% of the total amount of land water, but it is essential for a functional climate, environment and society. The challenge lies in the fact that some of the most hydrologically susceptible regions around the world have the worst maintained gauge network systems (Sivapalan et al., 2003).
Terrestrial water budgeting
Remote Sensing Applications in Terrestrial water Budgeting
The climate datasets are often validated with P estimates observed by satellites and/or meters (Sun et al., 2017). Runoff is calculated by physically based or atmospheric coupled hydrological models using satellite-based inputs and metadata at regional and global scales (Hassan, 2016; Rafiei Emam et al., 2017; Scanlon et al., 2019).
Complex River Basins
Hydrological Modeling
There is evidence of threshold-based runoff delay in hilly catchments of humid tropical or subtropical regions (Williams et al., 2002). Preferential flow is caused by active soil macropores dependent on soil cover (Shougrakpam et al., 2010; Sharma et al., 2013).
Objectives
Organization of Thesis
Satellite LSTs have similar problems to NDVI (Neteler et al., 2010). Other possibilities include empirical correlations using various meteorological, astronomical and geometric factors (Besharat et al., 2013). Due to the advantage of including macro-level simulations, the VIC model is used for global water balance studies (Bennett et al., 2018).
The Soil Water Assessment Tool (SWAT) model is one of the distributed hydrologic models and is being widely used for spatial analysis at the watershed level (Arnold et al., 1998). This is due to the active macropore network which increases the connectivity thus increasing the hydraulic conductivity in the vadose zone of the slopes (Graham et al., 2010). Furthermore, vegetation in the same ecoregion faces similar climatic and human conditions (Yang et al., 2017).
However, previously, the time series data of NDVI is used to delineate land surface phenology (Xiao et al., 2009). Parameters of macropore geometry for various LULC (modified for MODIS LULC from Das et al., 2014). It is shown by several research experiments that the events of runoff generation on the surface are rare in hills (Sarkar et al., 2015).
Literature Review
- Introduction
- Evapotranspiration and Energy Balance Models
- Moderate resolution imaging spectroradiometer (MODIS)
- Land surface Vegetation
- Land Surface Temperature
- Irradiance, albedo, emissivity and surface response
- Time-series reconstruction
- Harmonic analysis of time-series (HANTS)
- Data assimilation
- Dimensionality reduction
- Hydrological models
- Advances in process-based hydrological modeling
This suggests that the forest cover and preferential storage control the hydrological processes in Eastern Himalayan watersheds. With the previous studies and evidence of macropores, a specialized hydrological model for surface and sub-surface water balance was developed exclusively for complex watersheds of Eastern Himalaya. It was used as a demonstration with theoretical saturated hydraulic conductivity and infiltration rate on Subansiri watershed.
The unavailability of satellite data limits the access to monitor and understand the hydrological processes based on time series. A brief history of hydrological models used for water balance studies is also discussed to understand the approach of dealing with hydrological process in a variety of cases.
Reconstruction of Land Surface Vegetation
- Introduction
- Land surface phenology
- Data used
- Methodology
- Reference phenology curve
- Moving offset method (MOM)
- Results and Discussion
- Robustness of MOM
- Seasonality trait in different approaches
- Fitting performance
- Conclusion
Satellite data shortages and complex topography were understood to be the two crucial challenges in monitoring the energy and water budget in mountainous watersheds. Techniques to reconstruct the time series variables derived from satellite remote sensing for energy budgeting are therefore discussed with a focus on data-deficient regions. This was followed by an overview on principal component analysis technique which is widely used to reduce the complexity in vector dimensions.
It was used with HANTS, a popular NDVI reconstruction algorithm, for years using MODIS NDVI time series. MOM's physical assumption also helped recover the seasonal feature better than other methods, and HANTS smoothed the NDVI time series to obtain high-quality NDVI data.
Reconstruction of Land Surface Temperature
- Introduction
- Kernel density estimator
- Data used
- Methodology
- Temporal matching
- Temporal assimilation
- Spatial assimilation
- Results and Discussion
- Validation using MODIS original LST
- Validation with ground data
- Uncertainty analysis
- Conclusion
Hysteresis effect of runoff of the Heihe River on vegetation cover in the Ejina Oasis in Northwest China. A proposal for the Temporal Window Operation(TWO) method to remove high frequency noise in AVHRR NDVI time series data. Ts and Ta are ground surface temperature and air temperature in ℃, respectively; ra is the aerodynamic resistance in s m⁄, the diffusion resistance of the air layer.
Estimation of LEs and LEc requires the separation of the earth's surface temperature, which represents the mixed temperature. The volumetric fraction of IC macropore volume as a function of depth can be written in terms of the constant Pic,0 and the function F as shown in Eq.
Surface Water and Energy Budgeting
Introduction
The Two Water World hypothesis (Renée Brooks et al., 2010; McDonell, 2014; Berry et al., 2018) is an emerging concept that advocates that streams and trees return various pools of water to the hydrosphere. However, previous studies have shown that focusing on dominant processes can help overcome these complexities rather than capturing unnecessary details (Sivapalan, 2003; Graham et al., 2010). Several land-based water budgeting studies use these two variables as decisive parameters to regulate other components of water budgeting.
The focus of many of the current studies on terrestrial water budgeting is on the utilization of hydrological products from global hydrological models (GHM). Since ET estimated from GHM generally has a coarse resolution, the partitioning of dependent terrestrial water budget at complex watersheds may not be approximate.
Methodology
- Data preparation
- Surface energy and water budget
- Hydrological efficiency and resilience
- Indicators of hydrological resilience
The 90 m High Resolution Radar Topography Mission (SRTM) was used to calculate Ri and Rd. It was used as the rainfall source in the water budgeting after being remodelled to 1 km resolution for compatibility. The three-temperature model (3T model) developed by Tian et al. 2013) was used to calculate spatio-temporally consistent ET at the 16-day scale as shown in Figs.
Therefore, a new approach was used to correct for the heterogeneity of radiation received in mountainous topography. Later it was used together with daily P-time series for the inspection of the water availability as well as other hydrological diagnosis and indications on the mountainous topography of the study area.
Results and Discussion
- Seasonality
- Hydrological efficiency of various LULC
- Resilience hotspots
- Influence of forest on hydrologic resilience
Interestingly, ET in the study area increases and decreases according to the onset and onset of the monsoon. However, the spatial variability in ET excess indicated the control of LULC on the surface water budget. Most of the CRP and SVN lie in the lowlands and receive the highest annual P.
Annual daily median of precipitation and evapotranspiration and annual efficiency (η) for different LULC in the study area. However, the results in the rest of the mountain stretch suggest efficient use of stored water from the monsoon in the following seasons.
Conclusion
Schematic flow diagram of the developed model for surface and subsurface water balance in hilly watersheds. These grids have variable threshold runoff generation (Tsur) and hydraulic conductivity (Ksat) of the perched aquifer in spatial dimension. The watershed is divided into two regions, upper and lower, to decode the model results.
Most of the study area is covered by grassland in the higher regions and forest in the lower regions. The eastern Himalayan basins, located in northeastern India, are one of the most frequently cloudy regions in the world.
Hydrological Modeling for Hilly Watersheds
- Introduction
- Macropores
- Methodology
- Model concept
- Sub-surface characterization
- Micro-watershed characterization
- Water flow and balance
- Calibration and validation scheme
- Results and Discussion
- Surface and sub-surface flow
- Runoff response
- Conclusion
Estimating discharge in high mountain regions with improved methods using multisource remote sensing: A case study of the Upper Brahmaputra River. Spatio-temporal pattern extraction of cropping systems from NDVI time series using a combination of spline and HANTS algorithms: A case study for Shandong province. On the use of digital elevation model to estimate solar radiation in areas with complex topography.
RZAh is a parameter that can be used to describe the growth of the volumetric distribution curve (R) along the thickness of the A-horizon. A modified SRTM DEM at 1 km was used for spatial scale model compatibility.
Conclusion and Recommendations
Brief Review of the Work Done
However, inconsistency in satellite data propagates producing inconsistency in observation and understanding of the hydrological process. The land surface vegetation condition and temperature are two of the essential variables used to estimate water loss or evapotranspiration (ET). It was found that most watersheds had the best relationship with vegetation fraction and bedrock depth.
A socio-hydrological conceptual model of human and water co-evolution: case study of the Tarim River Basin, western China. Observed changes in upper atmosphere irradiance and upper ocean heating are robust within uncertainty. The macropore volume fraction of the two domains, the main bypass (Vmb) and the inner catchment (Vic) are functions of depth as presented in Eq.
In the horizontal plane, the distribution of the macropores determines the functional horizontal shape of the macropores, which forms the basis for the calculation of several important parameters.
Literature Review
Reconstruction of Land Surface Vegetation
Reconstruction of Land Surface Temperature
Surface Energy and Water Budgeting
Monitoring evapotranspiration (ET) and precipitation (P) at the surface level is expected to reveal some of the fundamental knowledge of the ongoing hydrological processes. Investigating the effect of temporal sampling frequency on DSCOVR observations using GEOS-5 Nature Run Results (Part I): Earth's radiation budget. Evaluation of the harmonic analysis method for surface soil heat flux estimation: a case study in the Heihe River basin, in: Jackson, T.J., Chen, J.M., Gong, P., Liang, S.
Comparison of the results of a rainfall simulator on a small plot and a rainfall simulator on a large plot - Effects of land use and land cover on surface runoff in Alpine catchments. Thus, the extraction of the phenological pattern is often used as an important feature of LULC classification methods (Friedl et al., 2002; Padhee et al., 2017). Hydraulic conductivity (K) is defined as the ability of water to penetrate through the pores of an aquifer.
The aquifers are believed to be near saturated in the rainy seasons, with the value of K being close to Ksat in the near-peak period of the season.
Hydrological Modeling for Hilly Watersheds
Recommendations for Future Research
This work used some of the archived papers which characterized the subsurface of the eastern Himalayan region by considering the macropore, root zone and bedrock dynamics through distributed dye tracer. Simulation of runoff generation and its spatial relationship with environmental factors in the Sancha River Basin: The southern source of the Wujiang River. The availability of correct SNDVIref for each pixel is important for implementing the proposed pre-filling method (Section 3.4.2).
In the presence of a reference surface of dry soil with no significant change in atmospheric conditions around it, the ra of the dry soil and the ra of the drying soil are approximately equal to each other;. 2007) established the thresholds NDVImax and NDVImin selection method, in which they can be calculated from the lower and upper 3% tails of the NDVI distribution within the scene. The dominance of a pixel that goes only soil evaporation, only vegetation transpiration or evapotranspiration at a pixel depends on category of the specific pixel.
But the requirement of this hydrological model is a saturated hydraulic conductivity (Ksat) rather than a general K to calculate the decay of the flow with time (Eq. 6.5).
