Effects of wetland conversion to farming on water quality and sediment and nutrient retention in a tropical catchment

Abias Uwimana

Research output: Thesisinternal PhD, WU

Abstract

The study used a combination of landscape-scale synoptic surveys (catchment, reaches) and mesocosm surveys (experimental plots) to assess the impacts of conversion of natural valley-bottom wetlands to farming land on the water quality and retention of sediment and nutrients. The results showed that temperature, pH, electrical conductivity and dissolved oxygen concentration decreased, and total suspended solids (TSS) increased with storm water increase. Nitrogen (TN) and phosphorus (TP) accumulated in the catchment during the dry season and washed into the water courses during the early stages of the higher flows, with subsequent lower concentrations at the end of the rains due to dilution. Large proportions of the annual loads of TSS, TP and TN (93%, 60% and 67%, respectively) were transported during rainfall events that occurred in 115 days. Fishponds acted as temporal traps of TSS, TN and TP at the early stages of farming, and were a source of and TN and TP at the end of the farming period, in contrast to rice farming that generated sediments and nutrients early in the farming period and trapped them at the end of the farming season. Wetlands mostly acted as sinks but sometimes as a source of sediment and nutrients.

Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • Wageningen University
Supervisors/Advisors
  • Irvine, K.A., Promotor, External person
  • van Dam, A.A., Co-promotor, External person
Award date28 Nov 2019
Place of PublicationLeiden
Publisher
Print ISBNs9780367859732, 9789463950732
DOIs
Publication statusPublished - 2019

Fingerprint

wetland
catchment
phosphorus
water quality
nutrient
sediment
mesocosm
water retention
electrical conductivity
dry season
dissolved oxygen
dilution
rice
valley
rainfall
effect
nitrogen
temperature
water

Cite this

@phdthesis{1dab7cc1a2c2496d8a244288cd72fda8,
title = "Effects of wetland conversion to farming on water quality and sediment and nutrient retention in a tropical catchment",
abstract = "The study used a combination of landscape-scale synoptic surveys (catchment, reaches) and mesocosm surveys (experimental plots) to assess the impacts of conversion of natural valley-bottom wetlands to farming land on the water quality and retention of sediment and nutrients. The results showed that temperature, pH, electrical conductivity and dissolved oxygen concentration decreased, and total suspended solids (TSS) increased with storm water increase. Nitrogen (TN) and phosphorus (TP) accumulated in the catchment during the dry season and washed into the water courses during the early stages of the higher flows, with subsequent lower concentrations at the end of the rains due to dilution. Large proportions of the annual loads of TSS, TP and TN (93{\%}, 60{\%} and 67{\%}, respectively) were transported during rainfall events that occurred in 115 days. Fishponds acted as temporal traps of TSS, TN and TP at the early stages of farming, and were a source of and TN and TP at the end of the farming period, in contrast to rice farming that generated sediments and nutrients early in the farming period and trapped them at the end of the farming season. Wetlands mostly acted as sinks but sometimes as a source of sediment and nutrients.",
author = "Abias Uwimana",
note = "WU thesis 7391 CRC Press/Balkema is an imprint of the Taylor & Francis Group, an informa business Ph.D. thesis UNESCO-IHE Institute for Water Education, 2019 Includes bibliographical references. - With summaries in English and Dutch",
year = "2019",
doi = "10.18174/497779",
language = "English",
isbn = "9780367859732",
publisher = "CRC Press/Balkema",
school = "Wageningen University",

}

Effects of wetland conversion to farming on water quality and sediment and nutrient retention in a tropical catchment. / Uwimana, Abias.

Leiden : CRC Press/Balkema, 2019. 131 p.

Research output: Thesisinternal PhD, WU

TY - THES

T1 - Effects of wetland conversion to farming on water quality and sediment and nutrient retention in a tropical catchment

AU - Uwimana, Abias

N1 - WU thesis 7391 CRC Press/Balkema is an imprint of the Taylor & Francis Group, an informa business Ph.D. thesis UNESCO-IHE Institute for Water Education, 2019 Includes bibliographical references. - With summaries in English and Dutch

PY - 2019

Y1 - 2019

N2 - The study used a combination of landscape-scale synoptic surveys (catchment, reaches) and mesocosm surveys (experimental plots) to assess the impacts of conversion of natural valley-bottom wetlands to farming land on the water quality and retention of sediment and nutrients. The results showed that temperature, pH, electrical conductivity and dissolved oxygen concentration decreased, and total suspended solids (TSS) increased with storm water increase. Nitrogen (TN) and phosphorus (TP) accumulated in the catchment during the dry season and washed into the water courses during the early stages of the higher flows, with subsequent lower concentrations at the end of the rains due to dilution. Large proportions of the annual loads of TSS, TP and TN (93%, 60% and 67%, respectively) were transported during rainfall events that occurred in 115 days. Fishponds acted as temporal traps of TSS, TN and TP at the early stages of farming, and were a source of and TN and TP at the end of the farming period, in contrast to rice farming that generated sediments and nutrients early in the farming period and trapped them at the end of the farming season. Wetlands mostly acted as sinks but sometimes as a source of sediment and nutrients.

AB - The study used a combination of landscape-scale synoptic surveys (catchment, reaches) and mesocosm surveys (experimental plots) to assess the impacts of conversion of natural valley-bottom wetlands to farming land on the water quality and retention of sediment and nutrients. The results showed that temperature, pH, electrical conductivity and dissolved oxygen concentration decreased, and total suspended solids (TSS) increased with storm water increase. Nitrogen (TN) and phosphorus (TP) accumulated in the catchment during the dry season and washed into the water courses during the early stages of the higher flows, with subsequent lower concentrations at the end of the rains due to dilution. Large proportions of the annual loads of TSS, TP and TN (93%, 60% and 67%, respectively) were transported during rainfall events that occurred in 115 days. Fishponds acted as temporal traps of TSS, TN and TP at the early stages of farming, and were a source of and TN and TP at the end of the farming period, in contrast to rice farming that generated sediments and nutrients early in the farming period and trapped them at the end of the farming season. Wetlands mostly acted as sinks but sometimes as a source of sediment and nutrients.

U2 - 10.18174/497779

DO - 10.18174/497779

M3 - internal PhD, WU

SN - 9780367859732

SN - 9789463950732

PB - CRC Press/Balkema

CY - Leiden

ER -