A comparative assessment of HEC-HMS and VIC hydrological models for simulating hydrological processes in Cauvery River Basin, India

<p>The hydrological cycle is governed by a number of complex processes which occur at different spatial and temporal scales. Hydrological modelling plays an integral role in enhancing the understanding of hydrological behaviour and process complexities at a range of scales. Different hydrological models have various strengths in the representation of hydrological processes. The performance and applicability of each hydrological model can differ between catchments due to several catchment characteristics and dominant hydrological processes. With a wide variety of model structures, it is important to evaluate how different hydrological models capture the process dynamics in various catchments. This study aims at a comprehensive evaluation of the performance of two widely used hydrological models, namely, the HEC-Hydrologic Modeling System (HEC-HMS) and the Variable Infiltration Capacity (VIC) model, in simulating various water balance components in the sub-catchments of the Cauvery River Basin which is a major river basin in Peninsular India. The basin is characterized by extensive regional variability in land use patterns, water availability, and water demands. The chosen models differ in their model structure complexities, methods adopted for simulation of water balance components, and the representation of geographical information, meteorological and physiographical inputs. The models are calibrated with respect to the observed streamflow at various gauge locations, and the simulated water balance components such as evapotranspiration and baseflow are assessed at annual and seasonal time scales. Also, the impact of the representation of the spatial distribution of input variables and model parameters (lumped versus distributed) are evaluated among the models. This work provides valuable insights into the applicability of various hydrological models in simulating hydrological processes in catchments with high regional complexities. Also, this work aids in the identification of effective models and model parameters which can be useful for hydrological data transfers between catchments as well as predictions in ungauged basins.</p>

The identity of Rasbora neilgherriensis (Teleostei: Danionidae), with a re-description

Rasbora neilgherriensis Day, long considered a synonym of Rasbora daniconius or Rasbora dandia, is re-described and shown to be a valid species based on an examination of type and recently-acquired topotypical specimens from the Western Ghats of India. The species is characterised by a complete lateral line with 32–34 pored scales on body, ½5–6/1/2½ scales in transverse line on body, a mid-lateral stripe that is 2½ scales wide anterior to the pelvic fin and 1–1½ scales wide on the caudal peduncle, and a caudal fin that is emarginate to forked with broadly rounded lobes. The species was recorded from the Cauvery River Basin in Kerala and Tamil Nadu, India, at elevations ranging from 710 m to 2015 m above sea level, in stream stretches with relatively denser riparian canopy cover.

Evaluating hydrological signatures and catchment similarities to estimate model parameters in Cauvery river basin, India

<p>Catchments are complex self-organizing environmental systems for which the form, drainage network, channel geometries, soil and vegetation, are all an outcome of co-evolution and adaptation to the ecological, geomorphologic and land-forming processes. Quantification of hydrological signatures provides vital information about the complex system properties and the functional behaviour of catchments. This work aims at evaluating catchment similarity with respect to geomorphology and hydrological signatures such as runoff ratio, flow duration curves and peak flows for calibrating and upscaling model parameters. The study is carried out on the sub-catchments of Cauvery river basin which is a major river basin in Peninsular India. The basin is characterized by extensive regional variability in surface and groundwater availability and large-scale shift in land use patterns in recent decades. With a significant number of anthropogenic interventions such as check dams and reservoirs, the basin faces water management challenges at the local, regional and basin scales. Hydrological signatures derived from elevation, streamflow and meteorological data are used to evaluate geomorphologic and hydrological similarity between the sub-catchments. We employ the physically based macroscale Variable Infiltration Capacity (VIC) model coupled with a routing model to simulate the streamflow. Streamflow simulations are carried out for various sub-catchments delineated based on discharge gauging stations. Model parameters are estimated and hydrological signatures are assessed for effective model calibration. Impact of interventions on flow signatures at the catchment scale is also assessed. This work can significantly improve the scientific understanding of variability of hydrological processes at various scales and provide useful insights for development of scaling relationships. It can also aid in examining the model parameter transferability across scales.</p>