Tab-contacts-off Tab-scientific-on


Main Product 2 (MP2): The DeSurvey Forecasting Product : Integrated Assessment Model (IAM)


Authors:

Hedwig van Delden (RIKS), Mike Kirkby (Leeds University), Bernhard Hahn (RIKS) bmhahn@riks.nl


1. Introduction

Land degradation is the main desertification effect on natural resources. Climate variability in combination with socio-economic processes acting on land may induce a reduction of resource potential and hence land degradation.

 

Any forecasting attempt to increase societal early warning capacity has to build up on the interaction between climate and socio-economics on the land. The MP2, (DeSurvey IAM) is an integrated Policy Support System developed with the aim to support policy makers having to deal with desertification-friven land degradation at the short-medium term timescales.

 

Using the DeSurvey IAM, policy makers can carry out an integrated assessment of the impact of different external factors and policy options on a number of indicators relevant to desertification.

 

The DeSurvey IAM has been developed with the objective to address a number of policy themes concerning regional development and land degradation. Problems, goals, policy options and policy indicators have been collected and structured for each of these themes, and translated into a conceptual framework.

 

Based on this framework a policy support system is designed and developed
incorporating socio-economic as well as physical models.
By using policy themes as a starting point for model integration and by linking the model to policy relevant indicators we intend to support policy makers at the regional level by providing assistance in:

  1. Understanding the important processes in the region as well as their interaction;
  2. Identification of current or future problems in the river basins;
  3. Impact assessment of possible policy measures to mitigate the problems;
  4. Evaluation of the different alternatives.

 

The DESURVEY IAM is generic for arid and semi-arid regions. It builds forward on the MODULUS and MEDACTION POLICY SUPPORT SYSTEM (PSS) that have been developed in previous European Research projects.

 

The previous versions of the system have been applied to the Marina Baixa (Spain), the Argolidas (Greece) and the Guadalentín river basin (Spain).

 

The current version is applied to the Jeffara region in Tunisia. Focus in the development of the system is on the scientific and software integration of models with different spatial and temporal scales and the applicability of such a system for the envisaged end-users, the policy makers and planners in the river basin.

 

 

2. Technical description of (MP2) the DeSurvey IAM

The core of the DESURVEY IAM is developed from an integrative point of view rather than a comprehensive one. Meaning that focus has been on dynamic integration of simple models, rather than in depth sectoral modelling.

 

In the DESURVEY IAM the level of complexity of the models are limited by:

  • the emerging fact that complex process models are not necessarily better than simple process models;
  • the logic that it is better to have a parameterisable, validatable simple model than an unparameterisable non-validatable complex one;
  • the reality that data for parameterisation, calibration, and validation is time consuming and expensive to obtain and is lacking throughout much of the Mediterranean.

 

The DESURVEY IAM integrates models with different paradigms and temporal and spatial resolutions. For every model is described, in the section General information at the beginning of the page, what its characteristics are, on what resolution it runs and what equations and data are used. Moreover, in the equations of the different sub-models is indicated with indices if the model runs on a yearly (y), monthly (m), daily (d) or sub-daily (ts) time step. The equations also show how integration over different temporal and spatial resolutions is taken into account.

 

The approach consists of setting up a dynamic environment where the Model Building Blocs (MBB) interact as to dynamically update a set of indicators which are relevant to evaluate desertification status and mitigation options.

 

The DESURVEY IAM calculates as part of its dynamic (sub-)model outputs a large series of spatial indicators in the fields of desertification & land degradation, water management and agricultural practice.

 

This is possible because the DESURVEY IAM includes the dynamic models required to update the spatial data layers that form the basis of the indicators. Based on its dynamic indicators (all available simultaneously and per simulation time step), the system enables exploring and assessing the effects of mitigation measures on the desertification status of the entire watershed, or on a precise
location in the watershed (spatial entities of 1 ha or 1 km2), on which they are targeted.

 

 

3. Implementation and software tools

The DESURVEY IAM has been designed to be run at 1 km and 0,01 km spatial resolution. It was developed and run under GEONAMICA®. GEONAMICA® is the object oriented application framework [Fayad, et al. 1999] developed by RIKS to build decision support systems based on spatial modelling and (geo)simulation.

 

It has been developed over the past 15 years and has been used to generate
integrated spatial decision support systems, such as WADBOS [Engelen, et al. 2003a], ENVIRONMENT EXPLORER [Engelen, et al.2003b], MEDACTION [Van Delden, et al. 2007], XPLORAH [Van Delden, 2008] and MOLAND [Barredo, et al. 2003]. Besides these, RIKS has used GEONAMICA® to develop METRONAMICA, a template SDSS that includes a local dynamic land use interaction model, a regional interaction model and/or a transport model – depending on the exact
version.

 

It can be used to set up a specific SDSS without the need for additional software development by filling the system with data, calibrating the model and training the users. In ISDSSs, such as the ones mentioned above, we can distinguish three major components: a database to store information used by the system – mostly raster or vector map data, time series data and cross-sectional data –, a
model base to manage the models that are used and a user interface to enable the user of the system to interact with it.

 

Setting up each of these components and letting them work together should be
facilitated by the application framework as much as possible.
GEONAMICA® offers set components for the storage of map data, time series and cross-sectional data.

 

It provides a modelling framework based on the Discrete Event System Specification (DEVS) formalism [Zeigler, et al. 2000] and includes a model controller that manages the models, makes sure they interact properly and tells each model when to perform certain, predefined actions.

 

To create a user interface, GEONAMICA® includes a skeleton structure and a rich class library of user interface components, such as map display and editing tools, list and table views and two-dimensional graph editing components.

 

The strength of GEONAMICA® lies in the fact that the modelling framework provides a generic structure for the models that allows them to be integrated more easily, while enabling complex dynamic models to be executed efficiently.

 

The environment is set up in such a way as to enable users to run simulations interactively, by allowing them to intervene in the system and observe the results of their actions directly in comprehensive manner or save the results to persistent storage for more elaborate analysis or presentational purposes.

 

In the DeSurvey project the GEONAMICA® framework has undergone a major re-design to be able to integrate models with different spatial and temporal resolutions and based on different modelling paradigms in a more flexible and scientifically correct manner.

 

MP2 is first applied to the Oum Zessar watershed (Tunisia) because of the availability of data and models for this region as well as the interest expressed by both regional researchers and stakeholders. MP2 has reached the status of first version prototype to be used on tutorial supervision. Users of different levels have been involved in its development, either in training or as visitors.

 

 

Effect of climatic change on crops of Castilla-La Mancha

The UCLM group has developed a study about the effects of different scenarios of Climatic Change on main crops of Castilla-La Mancha. The considered scenarios vary from an average temperature increase of 0.5 to 1.7ºC and a average rainfall decrease of -0.8 to -12%. Two rainfed crops (Winter barley and grape) and four irrigated crops (Spring barley, maize, garlic and grape) have been studied.

 

The increase of temperature may increase crops water requirements, mainly in Summer time. However, frost period may decrease and crops may grow faster.
Rainfall decrease will mainly affect to Spring and Summer crops, usually under irrigated conditions. However, rainfall increases in Winter time will favour rainfed crops. Anyway, rainfall variations are not so high. For this reason, the impact on crops will be low but negative.

 

Combining both effects will be possible to change seeding dates in order to fit the growing season of each crop to the most suitable time. This way, the effect of higher evapotranspiration rates and lower rainfall may be reduced. Irrigated cereals will increase their water requirements on Summer time, while Spring crops will maintain or decrease water requirements. Rainfed cereals will increase yield because of higher temperatures and suitable rainfall. Rainfed or irrigated tree crops offer different conclusions.