Featured hydrological tools:

1. 1.AWE-GEN
   

2. 2.Tethys-Chloris
   

3. 3.tRIBS
   

4. 4.tRIBS+VEGGIE

3. tRIBS

In its early developmental stages, tRIBS was an event-based model operating on a raster grid cell computational domain (RIBS, Garrote and Bras, 1995). The model has been subsequently extended to perform on a continuous basis with the addition of a new infiltration scheme for multiple storm events and hydrologic redistribution during interstorm periods due to groundwater flow and evapotranspiration demand. In addition, developments in TIN-based terrain modeling have also been incorporated into the model by restructuring the computational architecture. No longer bound to a raster grid, the computational domain is adjusted to better fit the terrain, allowing for significant savings in computation demand. In this framework, the Voronoi cell serves as the essential element for hydrologic modeling.

In its current state, tRIBS is capable of using the spatially distributed terrain data to their fullest capacity, while maintaining the efficiency required for treating larger watersheds. In addition, the model is capable of using other spatially distributed descriptors of the basin properties, specifically the soil type, vegetation and land cover data. Coupled with the ability to ingest precipitation estimates and forecasts from NEXRAD-based maps, tRIBS is able to take advantage of driving reasons for utilizing radar rainfall data, spatial coverage and temporal/spatial variability.

Primary tRIBS web-page is maintained by our colleague and collaborator Prof. Enrique Vivoni at:

http://vivoni.asu.edu/tribs.html

References

Garrote, L. and Bras, R. L. (1995). A Distributed Model for Real-time Flood Forecasting using Digital Elevation Models. Journal of Hydrology. 167: 279-306.

Ivanov, V.Y., Vivoni, E.R., Bras, R.L., and Entekhabi, D., (2004). Catchment hydrologic response with a fully-distributed triangulated irregular network model. Water Resources Research, 40(11), W11102, doi:10.1029/2004WR003218.

2. Tethys-Chloris (T&C)

The  idea to develop Tethys-Chloris model originates from the emerging interest that in the last ten years has been reversed toward eco-hydrological studies and related scientific questions. According to the spirit of “HYDROWIT” group a physical-based mechanistic tool has been developed to account for the coupled interactions of energy-water-vegetation in a variety of environments and climates where water is the key component. Applications can span from temperate Mediterranean climates to cold semiarid mountains environment. Tethys-Chloris applications aim to highlight eco-hydrological patterns and dynamics through numerical simulations with the will to solve or to sharp scientific questions.  All essential components of hydrological cycle are included.  Energy and mass exchanges in the atmospheric surface layer are treated thoroughly with an accurate resistance analogy scheme. A simplified module of saturated and unsaturated soil water dynamics governs the subsurface hydrology.  Up to two layers of vegetation (e.g. trees and grasses) can be accounted for. In cold environment a snowpack evolution module controls the energy exchanges, the snow accumulation and the snow melting that can be eventually mediated by vegetation interactions. Vegetation structure and dynamics are parsimoniously parameterizes including plant life-cycle processes, photosynthesis, phenology, carbon allocation and tissues turnover.

Land-Surface Hydrological Components

1. •absorption, reflection, and transmittance of solar shortwave radiation and atmospheric longwave radiation;
   

2. •sensible and latent heat fluxes, partition of latent heat into evaporation and transpiration, ground heat flux and incoming heat with precipitation;
   

3. •resistance scheme for water and energy fluxes, including aerodynamic resistance, leaf boundary layer resistance, soil resistance and stomatal resistance; 
   

4. •snow hydrology component, including snowpack energy balance, snowmelt and snow interception;
   

5. •rainfall interception, throughfall,  stem flow and splash erosion; 
   

6. •infiltration and water movement into a multi-layer soil including unsaturated zone dynamics, saturated zone and different types of  runoff formation. 
   

1. •stomatal physiology and photosynthesis.  These processes are highly coupled with the hydrological components and  the vegetation dynamics 
   

Vegetation Dynamics Components

1. •net primary productivity and plant respiration;
   

2. •carbon allocation and translocation to and from carbon compartments;
   

3. •tissue turnover and stress-induced foliage loss; 
   

4. •carbon balance; 
   

5. •vegetation phenology; 
   

The model simulates the energy and water budgets of bare soil,  vegetated, water and, snow covered surfaces for a basic computational element. A computational element typically represents an area with similar topographic features that can span 25-1000 m2. The union of many computational elements may form a hillslope or a watershed. Spatial distributed applications of Tethys-Chloris explicitly consider  topographic representation of the terrain, and interaction  with the neighbors elements.  Such interactions are represented through surface and subsurface moisture transfers among the elements. A scheme of subsurface and surface flow routing is thus implemented within Tethys-Chloris.

The model resolves the mass and energy budgets at the hourly scale, and the carbon vegetation dynamics at the daily scale. Vegetation and hydrology interacts at fine time scales through the influence of biochemical process on energy and water fluxes. Water availability on turn influences vegetation growth, health and structure in a longer time scale, leading to a wonderful coupled natural mechanism. 

The model names may seem unfamiliar, however… Tethys (Greek: Τηθύς)  in Greek mythology, was an archaic Titaness and aquatic sea goddess and she was considered as an embodiment of the waters of the world. Chloris (Greek: χλωρις),  was a Nymph associated with spring, flowers and new growth … thus nothing could be more familiar to us. 

References

Fatichi, S., V.Y. Ivanov, and E. Caporali (2012). A mechanistic ecohydrological model to investigate complex interactions in cold and warm water controlled environments. 1. Theoretical framework and plot-scale analysis. Journal of Advances in Modeling Earth Systems, doi:10.1029/2011MS000086.

Fatichi, S., V.Y. Ivanov, and E. Caporali (2012). A mechanistic ecohydrological model to investigate complex interactions in cold and warm water controlled environments. 2. Distributed analysis. Journal of Advances in Modeling Earth Systems, doi:10.1029/2011MS000087.

1. AWE-GEN

Records of meteorological variables around the world are often very short, with substantial gaps and low spatial coverage. This creates a problem of data inadequacy in numerous  applications.  To overcome such problems, weather generators, as the tools capable of generating consistent time-series of climatic variables, have been proposed and used in the past.  Weather generators infer from meteorological variables of an observed climate set of parameters that allow to numerically  reproduce  continuous and longer  time series  of such  climate. Several studies on  agricultural and crop productivity,  water resource evaluation,  flood risk analysis, etc., requires the use of weather generators.  Other possible applications are related to the generation of inputs to hydrological models, ecosystem models, or in long-term land management and erosion studies. 

References

Fatichi, S.,  Ivanov, V.Y.,  E. Caporali (2011). Simulation of future climate scenarios with a weather generator, Advances in Water Resources, 34, 448–467, doi:10.1016/j.advwatres.2010.12.013

Ivanov, V.Y., Bras, R.L., and Curtis, D.C. (2007). A weather generator for hydrological, ecological, and agricultural applications, Water Resources Research, 43, W10406, doi: 10.1029/ 2006WR005364.