@article{fdi:010096405,
  title = {{H}ydrological regime shifts in {S}ahelian watersheds : an investigation with a simple dynamical model driven by annual precipitation},
  author = {{L}e {R}oux, {E}. and {W}endling, {V}. and {P}anthou, {G}. and {D}ubas, {O}. and {V}andervaere, {J}. {P}. and {H}ector, {B}asile and {F}avreau, {G}uillaume and {C}ohard, {J}. {M}. and {P}ierre, {C}. and {D}escroix, {L}uc and {M}ougin, {E}. and {G}rippa, {M}. and {K}ergoat, {L}. and {D}emarty, {J}{\'e}rome and {R}ouch{\'e}, {N}athalie and {E}tchanchu, {J}ordi and {P}eugeot, {C}hristophe},
  editor = {},
  language = {{ENG}},
  abstract = {{T}he {S}ahel, the semi-arid fringe south of the {S}ahara, experienced severe meteorological droughts in the 1970s-1980s. {D}uring and after these droughts, watersheds in the {C}entral {S}ahel have experienced an increase in the annual runoff coefficient (annual runoff normalized by annual precipitation). {W}e hypothesize that these increases correspond to regime shifts. {T}o investigate the timing of these regime shifts, we introduce a lumped model that represents feedbacks between soil, water and vegetation at the watershed scale and the annual time step. {T}his model relies on runoff coefficient as a constraint for the state variable and precipitation as unique external forcing. {F}our watersheds ({G}orouol, {D}argol, {N}akanb{\'e}; and {S}irba), with pluri-decennial observations (1950s-2010s), are modeled. {F}or each watershed, one million parameterizations of this model are sampled and run, and an ensemble of one thousand best parameterizations is selected based on observed runoff coefficients. {O}ur results show that this model can reproduce the trend of runoff coefficients. {F}or all watersheds, almost all selected parameterizations from the ensemble are bistable. {W}e define two alternative runoff coefficient regimes (a low and a high regime) by splitting with a threshold the bifurcation diagram of bistable parameterizations. {M}ost selected parameterizations undergo regime shifts: simulated runoff coefficients belong to the low regime in 1965 and to the high regime in 2014. {F}inally, we find that the year of the regime shift, defined as the year when the number of regime shifts is maximized, was 1971, 1972, 1973, 1983 for the {G}orouol, {N}akanb{\'e}, {D}argol and {S}irba watershed, respectively. {T}hese results were obtained with a parsimonious model which deliberately neglects fine-scale processes of {S}ahelian hydrology. {I}t would therefore be wise to supplement this analysis with other models - with varying levels of complexity - that also allow regime shifting. {O}verall, this article proposes simple ideas toward improving the modelling and characterization of hydrological regime shifts.},
  keywords = {{MALI} ; {BURKINA} {FASO} ; {NIGER} ; {ZONE} {SAHELIENNE} ; {ZONE} {SEMIARIDE} ; {GOROUOL} {BASSIN} {VERSANT} ; {DARGOL} {BASSIN} {VERSANT} ; {NAKANBE} {BASSIN} {VERSANT} ; {SIRBA} {BASSIN} {VERSANT}},
  booktitle = {},
  journal = {{H}ydrology and {E}arth {S}ystem {S}ciences},
  volume = {30},
  numero = {4},
  pages = {929--944},
  ISSN = {1027-5606},
  year = {2026},
  DOI = {10.5194/hess-30-929-2026},
  URL = {https://www.documentation.ird.fr/hor/fdi:010096405},
}