Preprints
https://doi.org/10.5194/hess-2021-581
https://doi.org/10.5194/hess-2021-581
19 Nov 2021
 | 19 Nov 2021
Status: this preprint was under review for the journal HESS but the revision was not accepted.

Modelling groundwater recharge, actual evaporation and transpiration in semi-arid sites of the Lake Chad Basin: The role of soil and vegetation on groundwater recharge

Christoph Neukum, Angela Gabriela Morales Santos, Melanie Ronelngar, Aminu Bala, and Sara Vassolo

Abstract. The Lake Chad Basin, located in the center of North Africa, is characterized by strong climate seasonality with a pronounced short annual precipitation period and high potential evapotranspiration. Groundwater is an essential source for drinking water supply as well as for agriculture and groundwater related ecosystems. Thus, assessment of groundwater recharge is very important although difficult, because of the strong effects of evaporation and transpiration as well as limited available data.

A simple, generalized approach, which requires only a small number of field data, freely available remote sensing data as well as well-established concepts and models, is tested for assessing groundwater recharge in the southern part of the basin. This work uses the FAO-dual Kc concept to estimate E and T coefficients at six locations that differ in soil texture, climate, and vegetation conditions. Measured values of soil water content and chloride concentrations along vertical soil profiles together with different scenarios for E and T partitioning and a Bayesian calibration approach are used to numerically simulate water flow and chloride transport. Average groundwater recharge rates and the associated model uncertainty at the six locations are assessed for the 2003–2016 time-period.

Model results show that interannual variability of groundwater recharge is generally greater than the uncertainty of the modelled groundwater recharge. Furthermore, the soil moisture dynamics at all locations are limited rather by water availability for evaporation in the uppermost part of the soil and by water uptake in the root zone than by the reference evapotranspiration.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.
Christoph Neukum, Angela Gabriela Morales Santos, Melanie Ronelngar, Aminu Bala, and Sara Vassolo

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on hess-2021-581', Anonymous Referee #1, 10 Dec 2021
    • AC1: 'Reply on RC1', Sara Vassolo, 16 Dec 2021
  • RC2: 'Comment on hess-2021-581', Anonymous Referee #2, 11 Jan 2022
    • AC2: 'Reply on RC2', Sara Vassolo, 19 Jan 2022

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on hess-2021-581', Anonymous Referee #1, 10 Dec 2021
    • AC1: 'Reply on RC1', Sara Vassolo, 16 Dec 2021
  • RC2: 'Comment on hess-2021-581', Anonymous Referee #2, 11 Jan 2022
    • AC2: 'Reply on RC2', Sara Vassolo, 19 Jan 2022
Christoph Neukum, Angela Gabriela Morales Santos, Melanie Ronelngar, Aminu Bala, and Sara Vassolo
Christoph Neukum, Angela Gabriela Morales Santos, Melanie Ronelngar, Aminu Bala, and Sara Vassolo

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Short summary
The Lake Chad Basin, located in the center of North Africa, is characterized by a short annual precipitation period and high potential evapotranspiration. Groundwater is an essential source for drinking water supply, agriculture and groundwater related ecosystems. Assessment of groundwater recharge is very important although difficult, because of the effects of evaporation, transpiration and limited available data.