These challenges can be addressed with a combination of the 3Is – Information, Institutions and Investments and an effort to integrate these approaches.
A description of the Investment, Institutions, and Information is described further by clicking on the I’S icon. Clicking on the hand icon will revert back to the homepage.
Interactive Figure: The Three I’s (Information, Institutions and Investments)
One of the major approaches in better managing watersheds is to improve the data, information, and knowledge base to better inform decisions related to planning and operations. Watersheds can be better managed through use of Monitoring Systems (in-situ, earth observation, crowdsourcing), Analytics (basin, precipitation-sheds, land use planning) and making associated data and knowledge publicly accessible.
Monitoring Systems: It is often said that you cannot manage what you cannot measure. Watersheds in the South Asia region need to improve their monitoring of natural resources (e.g., water, forests, land use) and related investments to improve their longer-term planning as well as short-term management. This includes- In-Situ Observations: These can be done through improved in-situ observations using sensors or smartphone apps.
Earth Observation: This involves enhanced use of a new generation of earth observation tools that can be used to detect forest loss, climate/weather indicators, droughts/floods, agriculture productivity, land use change, etc.
Analytics: These can be done with the support of a new generation of cloud computing (including free options) that could also be very useful in areas with limited connectivity. For example, new approaches to improve streamflow forecasting for the entire basin- GEOGLOWS which provides streamflow forecasts 15 days in advance with uncertainty boundaries based on ECMWF 51-model forecasts and historical streamflow estimation for the last 35 years.
Access: Making data and analytics more accessible in the public domain could help in better understanding the conditions in watersheds which is crucial for restoring areas with degraded water quality, as well as for protecting healthy waters from emerging problems. Also, there is strong need to support the development of online data using agreed protocols and formats and creation of free, online public-data services that can be accessed through open services and APIs to support further analytics and visualization. The availability of data in the public domain is challenging especially in transboundary watersheds, but a range of “disruptive” technologies are helping provide new avenues in this regard.
Sediment Modelling tools exist to measure and model sediment in a watershed. The model selection depends on factors such as the size of area – e.g. a farm plot or an entire river basin or on a specific concern – e.g. agricultural run-off or reservoir sedimentation as well as data availability. The most common source of erosion is water erosion and the tools to measure water erosion are the most developed and standardized. The tools used to measure erosion and sediment loss at a water-shed or basin scale can include any of the following used individually or in combination with each other: Sediment Loss and Transport Models, Sediment Yield from Catchments, Remote Sensing and Geospatial Imagery and Digital Elevation Models (DEMs).
1. Sediment Loss and Transport Models
Erosion and sediment loss models have been developed based on the results of rainfall simulator studies and the use of experimental erosion run off plots (FAO, 2019).
Both the above studies were extensively used to develop the Universal Soil Loss Equation (USLE), one of the most widely used mathematical models to understand erosion processes. In the development of the first version of the USLE over 10,000 annual records from plots and small catchments were analyzed to develop the empirical relationships embodied in the equation (FAO, 2019). The USLE, developed in the United States in the 1930s, was revised in 1993 to incorporate more advanced computerization and improved calculations leading to the Revised University Soil Loss Equation (RUSLE). Subsequently several other models have been developed based on similar principles but adapted on one or more parameters to account for improved data availability, differences in local geographic conditions or other specific requirements of the geographical area.
2. Sediment yield from catchments
Tools can also measure the water flow and suspended sediment concentration from catchments and river basins. Gauging stations are installed along a steam or river channel and devices measure the suspended sediment load of the water at set time intervals. Sediment yield at the measurement point is expressed as the mass of sediment per area of the catchment for a given time-period (for example, t km-1 yr-1). This method can be used in combination with gross estimates of erosion rates in the catchment to calculate the ratio delivered at the basin outlet to gross erosion within the basin – known as the sediment delivery ratio. The limitations of using this tool in isolation are: i) The sediment measured at the outlet is only a fraction of that eroded in the catchment, ii) sediment on hillslopes and along river courses causes a time lag between erosion in the catchment and sediment measurement and iii) the sediment transported in the river is derived from sources other than hillslope erosion (FAO, 2019)
3. Remote Sensing Technology
Remote sensing is increasingly being used a tool to facilitate field assessments of erosion, especially to understand rill and gully formation and may in the future supplant the use of model-based approximations of sediment loss, by measuring erosion using change detection through measurements like Light detection and range (LIDAR) and close-range photogrammetry through repeated surveys.
4. Geospatial Imagery and Digital Elevation Models (DEMs)
GIS (Geographical Information System) and DEMs are key sources of information to establish the boundaries of the basin, land-use land cover. They are integral to the process of sediment modelling as the process is best viewed on a GIS platform such as ArcGIS or QGIS. Sediment models use input data such as GIS data, Land use Land Cover Maps and information in tables - to present outputs such as the sediment load delivered to the stream and sediment retained by vegetation and topographic features.
5. Tangible Landscape
Complex spatial forms like watershed topography can be challenging to understand, given the high cognitive load. The cognitive work can be offloaded through 3D geospatial mapping, analysis and simulation. With Tangible Landscape one can hold a model of a watershed landscape and sculpt its topography allowing one to change the flow of simulated digital water, create new streams and plant forests etc. Tangible Landscape combines physical model with the digital model of a landscape enabling one to naturally feel, reshape, and interact with the landscape.