# Integrating human water uses in a regional scale distributed hydrological model: model evaluation

Flora Branger, Louise Mimeau, Louise Crochemore, Jeremie Bonneau, Baptiste Lévêque, Nathan Pellerin, Emilie Chaix, Ruben Kubina, Eric Sauquet, Marielle Montginoul, et al.

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## To cite this version:

Flora Branger, Louise Mimeau, Louise Crochemore, Jeremie Bonneau, Baptiste Lévêque, et al. Integrating human water uses in a regional scale distributed hydrological model: model evaluation. EGU General Assembly 2025, Apr 2025, Vienna, Austria. 12 p., 10.5194/egusphere-egu25-16477. [https://hal.inrae.fr/hal-05088974v1](https://hal.inrae.fr/hal-05088974v1) Submitted on 28 May 2025

HAL Id: hal-05088974

[https://hal.inrae.fr/hal-05088974v1](https://hal.inrae.fr/hal-05088974v1)

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Distributed under a Creative Commons Attribution 4.0 International License
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# Integrating human water uses in a regional scale distributed hydrological model :
## Model evaluation

F. Branger, L. Mimeau, L. Crochemore, J. Bonneau, B. Lévêque, N. Pellerin, E. Chaix, R. Kubina, E. Sauquet, M. Montginoul, and M. Rabotin

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# Natural water resources and human water uses

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Pressure = water use volume / natural discharge

<figure><img src="image_8.png" /><figcaption>Water use pressure on the Rhône@Beaucaire (100000 km²) (Vidal, 2019)</figcaption></figure>

* Multiple human water uses

* Pressure on natural resource already visible even in large river systems

* How will these interactions evolve with climate change ?

* Integration of water uses in hydrological models :

* improve our understanding of the system

* test water management adaptation scenarios
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# Incorporation of water uses in the J2000 distributed hydrological model

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* Fully distributed hydrological model with HRU concept (Krause et al., 2006)

* Irrigation (crop water need model)

* Drinking water abstraction and release

* Water retention and release through dams

Prescribed daily setpoint values
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# Application to the Rhône catchment

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* Natural hydrology validated on 254 gauging stations

(Branger et al., 2016; Morel et al., 2023)

* Parameterisation of water uses based on national and regional databases :

* BNPE : locations of water withdrawal points + sources (surface water / groundwater) for drinking water and irrigation

* Water Agency database on WWTPs

* RGA : irrigated surfaces, main irrigated crops and irrigation types

* Econometric model of water consumption

* Reconstruction of dam / derivation influences

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River reaches : **drinking water** and **irrigation** withdrawals, **WTTP release**

HRUs (groundwater) : **drinking water** and **irrigation** withdrawals
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# Model evaluation

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* 60 years simulation (1960-2019) at daily time step

* Evaluation against:

* Observed daily discharge at 63 gauging stations 1980-2010

* Surface water and groundwater withdrawal total volume 2012-2017 (BNPE)

* Monthly groundwater levels from 31 piezometers 2000-2019

* SPLI = standardized piezometric level index

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# Results : model evaluation

<table><thead><tr><th>Discharge</th><th>KGE</th><th></th></tr></thead><tbody><tr><td></td><td>with uses</td><td>natural</td></tr><tr><td>Min</td><td>-0.37</td><td>-0.37</td></tr><tr><td>Max</td><td>0.88</td><td>0.88</td></tr><tr><td>Median</td><td>0.62</td><td>0.64</td></tr><tr><td>Mean</td><td>0.54</td><td>0.55</td></tr></tbody></table>

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* No significant model performance modification regarding discharge

* Correct reproduction of water withdrawal for drinking water

* BUT :

* The model **severely underestimates** water withdrawal for irrigation (especially in groundwater)

* A few **unexpected results** !

<table><thead><tr><th>station</th><th>Precip [mm]</th><th>Obs [mm]</th><th>Sim_nat [mm]</th><th>Sim_uses [mm]</th></tr></thead><tbody><tr><td>X1225010</td><td>900</td><td>487</td><td>181</td><td>870</td></tr></tbody></table>
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# Reason #1: parameterisation of water uses components: release from WTTPs

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Obs --- Nat --- Uses

* Setpoint values for water release from WTTPs disconnected from water withdrawal:

* Release volume based on drinking water demand setpoint values

* Location of points

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* Artificial addition of water in some river reaches!

River reaches: **drinking water** withdrawal, **WTTP release**

HRUs (groundwater): **drinking water** withdrawal
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# Reason #1 : parameterisation of water uses components : irrigation

<table><thead><tr><th rowspan="2"></th><th colspan="2">BNPE</th><th colspan="3">J2000</th></tr><tr><th>Nb</th><th>Water withdrawal (Mm3/year)</th><th>Nb</th><th>Water demand (Mm3/year)</th><th>Water Withdrawal (Mm3/year)</th></tr></thead><tbody><tr><th>Reach AEP</th><td>102</td><td>2,7</td><td>63</td><td>2,2</td><td>2</td></tr><tr><th>Reach irrigation</th><td><strong>561</strong></td><td>1,1</td><td><strong>114</strong></td><td>1,9</td><td>0,93</td></tr><tr><th>HRU AEP</th><td>2608</td><td>0,4</td><td>2628</td><td>0,26</td><td>0,2</td></tr><tr><th>HRU irrigation</th><td><strong>1494</strong></td><td><strong>0,097</strong></td><td><strong>197</strong></td><td><strong>1,7</strong></td><td><strong>0,05</strong></td></tr></tbody></table>

* 311 irrigated HRUs vs 2055 withdrawal points in the BNPE database

* Assumption of 1 irrigation point per HRU

* Concentration of withdrawal points : **too much water demand for a single HRU**
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Reason #2 : missed natural hydrological
processes : groundwater

<figure><img src="image_24.png" /><figcaption>*Comparisons with piezometers*
(Kubina, 2024)</figcaption></figure>

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* J2000 values hit **min** or **max** thresholds → reservoirs either full or dry

* Not enough storage in the groundwater compartment for most geology classes

* Worsens the problem of water availability for irrigation
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# Conclusions

* Incorporation of water uses in a regional hydrological model

- Adding equations in the model is one thing, parameterisation is another!

- Additional difficulty due to the scale of the model: need to make simplifying assumptions

- Problems don't necessarily show in the simulated discharge

* Lessons learned

- Interest of using additional variables for model evaluation

- Need to design parameterisation strategies adapted to regional scale models and make sure they are consistent

- Still some work to do on natural hydrology

See presentation tomorrow on *Mountain Hydrology HS2.1.1*

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# Perspectives : future irrigation scenarios

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EXPLCRE2
Des futurs de l'eau

* Climate change : « purple » trajectory (hot and dry in summer)

* Irrigation scenarios based on bibliographical work (Chaix 2024)

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Thank you for your attention