Session FT 2.04

Shared Vision Models

Conveners

• Mexican Institute of Water Technology
• DHI Water and Environment

Lessons learnt

1. Models are no longer academic exercises. There is now a convergence of models and decision makers. Models are now open not only to experts, but also to the general public. The level of detail is now such that they aloud to avoid conflicts and take optimal or suboptimal decisions.
   
2. It is necessary to improve water supply taking into account economic and population growth and climate change. In the large aquifers in Southern US, population and economic growth caused the greatest challenges in water resources management. New alternatives such as storing seasonal runoff into groundwater basins to reduce evaporation and seawater desalination are now competitive even economically. Other alternatives are municipal sewage treatment for recharge and then potabilization and the use of conservation, in the form of diminution of per capita use, leakage control and water pricing.
   
3. Modelling is useful and fun. Models are used to project into the future. We must distinguish two kinds of models: those describing and understanding the system and perspective models to tell us what to do. There have been sad experiences on decisions made based on mathematical models. There is a concern on the sustainability of modeled systems and the proper ways of transference of models to users. Models can be used to avoid irrational decisions. We should not always do what models say. There are challenges incorporating stakeholders views into models
4. Mathematical and statistical models tend to underestimate maxima and overestimate minima. Probability of failure of models should be taken into account when there is high uncertainty in climate and hydrology; when it is ignored, results are catastrophic.
   

Key Messages

1. The main objective of this type of models is the integrated implementation of water resources, which implies public participation, information sharing, etc.
2. Water resources management is a complex task and transcends the boundaries of a single discipline. It is not a multidisciplinary, not even a transdisciplinary effort, but an interdisciplinary one. In this effort, experts in political science, economists and other specialists should participate along with water management professionals in order to properly communicate with stakeholders. Maturation of democratic systems implies consensus building and negotiation, where every actor wins and loses something. Models are an invaluable tool in this process.
3. Uncertainty in data and, more profoundly, in models should be taken into account. It should be kept in mind that models are only idealizations of reality and therefore are always perfectible.
   

Orientations for action

1. It is necessary to move the models usefulness from physical aspects description to real decision making tools which help to build a shared vision taking into account all concepts and actors.
2. More development is needed in environmental analysis.
3. Models are useful tools to guide discussions among stakeholders. However, results should be presented in an understandable way to everyone. All efforts should be documented and methodologies should be developed to build consensus and take decisions in a democratic environment with participation of every pertinent discipline.

Local Actions Presented

Mathematical modelling for consensus building in the Lerma Chapala basin, México

Álvaro A. Aldama, Mexican Institute of Water Technology, Mexico

Two mathematical models were developed to analyze diverse scenarios for water management in a highly confrontational environment in the basin. The use of the mathematical models was determinant to build consensus among the stakeholders and lead to a joint water management policy which was included in an agreement signed by them and published in the official newspaper.

Nitrate management in the Ringkoebing Fjord river basin, Denmark

Henrik Larsen, DHI Water and Environment, Denmark

Through the use of advanced mathematical models, measures were designed to minimize the nitrate pollution of the water resources of the river basin in a heavily cultivated area in western Denmark introducing the least possible limitation on agricultural practices.

Binational water management information system for the río Bravo/Grande basin, México/USA

Daene McKinney, University of Texas at Austin, USA

A geodatabase based on the ArcHydro data model was developed to assess risks and possible mitigation of droughts and floods, manage water rights, assess water quality and understand the hydrology of the basin. The geodatabase represents the first major attempt to establish a complete understanding of the whole basin.

Karnafuli river basin management, Bangla Desh

Emaduddin Ahmad, Institute of Water Modelling, Bangla Desh

A suite of mathematical hydraulic models are used as decision supports tools for the basin. Rainfall-runoff, hydrodynamic and 2D bay models are included and modules of salinity, sediment transport, water quality, flood forecasting and bank erosion are in operation. The modelling tools provide options to the stakeholders for the sustainable use of water resources.