University of Twente Student Theses
A model comparison between WWL Tabel and Regionaal for setting a water ordinance.
Zegers, L. (2024) A model comparison between WWL Tabel and Regionaal for setting a water ordinance.
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| Abstract: | In the Netherlands, the water boards are the responsible authorities for regional water management. Their tasks include managing water ordinances which affect the hydrological conditions in soil. Mismanaged hydrological conditions in soils can cause yield losses in agricultural production. When developing water ordinances, it is important to understand their potential consequences for the yield, and specifically to predict yield losses. Tools, such as the Waterwijzer Landbouw (WWL) can be used to quantify yield losses under different scenarios. WWL contains three models for such assessments: Maatwerk, Tabel and Regionaal. Tabel and Regionaal can quantify the yield losses on a regional level. The goal of this study is to judge the performance of Tabel and Regionaal and their (dis-)advantages. Theory: Regionaal is a sophisticated, geo-referenced time series model that predicts yield loss based on plant growth. It models plant growth and related yield losses on daily or weekly intervals with situation-specific input data such as hydrological conditions, climate data and soil conditions. Tabel also estimates the yield losses but based on a combination of (limited) conditions that generate pre-determined outputs. The database for Tabel has been developed based on outputs of Regionaal. These outputs were created by running different scenarios for a standard 30-year period. Methods: A multicriteria decision analysis supported by model runs and interviews were used for this study. The criteria covered result type, validity, verification, acceptability, practicality and effectiveness. The result type refers to the unit and dimensions of the model results, in this case both models output relative yield loss over a region for a certain period in years. Validity and verification represent the reliability of the models. Acceptability is the scope of approval of a model by the users and stakeholders. The practicality of the models is defined by the ease of use, understanding and computation time. Effectiveness covers how useful the results of a model are to formulate advice. The findings were used in a multicriteria decision analysis to conclude which model is more suitable for setting water ordinance policies. Validity and verification: This study found that both models have no existing research validating the models against real-world measurements. Only that Tabel had been validated against Regionaal. The verification of both models however is different: Regionaal is more verified since it is a deduction model predicting yield loss by simulating plant growth. Tabel, on the contrary, predicts the yield loss by predicting what Regionaal would have simulated. Acceptability: From the interviews it was concluded that interviewees felt more confident in the results of Regionaal than in Tabel. This was due to Regionaal simulating the plant growth daily or weekly instead of seasonally. Practicality: The practicality of Tabel is significantly better than Regionaal. Tabel is easier to use and requires significantly less computational power. Regionaal needs to simulate the plant growth daily or weekly for each raster cell of the to-be-modelled region. This simulation requires significantly more computation, which is a drawback. Effectivenes: Due to the longer computational time of Regionaal this research made a model run only for a dry period. These results are less useful when setting a water ordinance compared to yield losses over a 2 longer period such as from Tabel. This is due to water ordinance being set for general circumstances. This made Tabel scoring higher on the criterion of effectiveness. Conclusion: This study recommends the use of Tabel when setting water ordinance, since Tabel is easier and more feasible to use when simulating a thirty-year period. Although Regionaal is more verifiable than Tabel – due to Regionaal simulating plant growth daily or weekly – there is no hard evidence for this. Tabel has been validated against Regionaal and it was shown that Tabel overestimates drought yield loss in heavy clays during wet periods. The ease of use and quicker computation time of Tabel outweighs the validity and verifiability of Regionaal. In more specific research cases, like an extreme drought period, Regionaal is recommended, since that would require simulations of shorter time periods. |
| Item Type: | Essay (Bachelor) |
| Faculty: | ET: Engineering Technology |
| Programme: | Civil Engineering BSc (56952) |
| Link to this item: | https://purl.utwente.nl/essays/104569 |
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