@article{fdi:010094799,
  title = {{E}xploring the nexus between hydroclimatic variability, population growth, land use land cover change, and long-term upper {N}yong {B}asin {R}iver chemistry ({C}entral {A}frica rainforest)},
  author = {{K}omba, {D}. {E}. and {N}dondo, {G}. {R}. {N}. and {R}iotte, {J}ean and {A}udry, {S}. and {N}lend, {B}. and {N}nomo, {B}. {N}. and {B}oum-{N}kot, {S}. {N}. and {B}essa, {H}. {A}. and {F}ongoh, {E}. {J}. and {B}oithias, {L}. and {L}agane, {C}hristelle and {N}goupayou, {J}. {R}. {N}. and {N}tamak-{N}ida, {M}. {J}. and {E}tame, {J}. and {B}raun, {J}ean-{J}acques},
  editor = {},
  language = {{ENG}},
  abstract = {{H}ydrological and hydrogeochemical functioning of rivers depends on the relationship between climatic variability, land use and land cover change ({LULCC}), and population dynamics. {H}owever, there is a scientific gap on this relationship in the humid tropical zone of {C}entral {A}frica. {T}his study aims to fill this gap by examining the link between hydroclimatic variability, population growth, {LULCC}, and river water chemistry in the upper {N}yong basin ({UNB}). {A}tmospheric temperature and rainfall data were obtained from {C}limatic {R}esearch {U}nit gridded {T}ime {S}eries 4.07 ({CRU} {TS} 4.07), in {G}oogle {E}arth {P}ro 7 software. {D}emographic data were obtained by projection based on the 1976, 1987 and 2005 censuses, assuming population increase as in the past. {L}and use and land cover ({LULC}) maps for 2005-2020 periods were produced from {L}andsat images ({L}andsat 7 {ETM} + from 2005 to 2010 and {L}andsat 8 {OLI} from 2015 to 2020). {S}upervised classification with {M}aximum {L}ikelihood {A}lgorithm was used to classify the {L}andsat images in {A}rc{GIS} 10.8 {S}oftware. {T}hree {LULC} classes ({F}orest, impervious and agricultural surface and water) were successfully classified, with overall accuracies from 96.4 to 100%, and {K}appa coefficients from 88.4 to 100%. {T}he study also used 29-year (1994-2023) meteorological (rainfall), hydrological (discharge) and hydrochemical (water temperature [{WT}], p{H}, electrical conductivity ({EC}), alkalinity [{A}lk], {N}a+, {K}+, {C}a2+, {M}g2+, {NO}3-, {SO}42-, {F}-, {C}l-, {HCO}3- , dissolved organic carbon [{DOC}], silica [{S}i{O}2] and suspended particulate matter [{SPM}]) database provided by {M}ultiscale {TROPI}cal {C}atchment{S} critical zone observatory ({M}-{TROPICS} {CZO}) in the {UNB}. {T}he results show that population increased in {UNB} from 2.6 million to 4.1 million between 2005 and 2020. {T}his population growth has increased demands for food, housing, agricultural activities, etc. {T}o meet these demands, the populations have converted 1,207 km(2) of forest into impervious and agricultural surface (buildings, roads, agricultural land, etc.). {M}ore so, {LULC} classes have evolved from 2005 to 2020 as follows: 17,845 km(2 ) to 16,638 km(2) (-6.7%) for forest, 1,376 km(2 )to 2,587 km(2) (+ 88%) for impervious and agricultural surface, and 15 km(2) to11 km(2) (-26.7%) for water. {T}he increase in impervious and agricultural surface has led to increase in soil sealing, thus promoting increase runoff and, long term discharge. {D}espite the increase in discharge, a significant increase (p < 0.01) in p{H}, {EC}, {TDS}, cation and {NO}-3 concentrations were observed. {T}his increase was attributed to the discharge of household and industrial waste and wastewater into the environment and river, and probably due to a greater contribution of groundwater to surface water. {T}he groundwater contribution was supported by the significant decrease (p < 0.01) in {DOC} over the long term. {I}n addition, the significant decrease in {C}l-, {SO}42- , {A}lk, {HCO}3- , and {S}i{O}2 is associated with increased photosynthetic activity due to eutrophication of the {N}yong {R}iver, as well as the long term soil depletion of these chemical elements by slash-and-burn agriculture.},
  keywords = {{L}and use and land cover change ; {P}opulation growth ; {R}iver water chemistry ; {U}pper {N}yong basin ; {T}ropical ecosystems ; {CAMEROUN} ; {AFRIQUE} {CENTRALE} ; {ZONE} {TROPICALE} ; {NYONG} {BASSIN}},
  booktitle = {},
  journal = {{S}cientific {R}eports - {N}ature},
  volume = {15},
  numero = {1},
  pages = {27580 [29 p.]},
  ISSN = {2045-2322},
  year = {2025},
  DOI = {10.1038/s41598-025-11578-7},
  URL = {https://www.documentation.ird.fr/hor/fdi:010094799},
}