| Description |
1 online resource (151 pages) |
| Series |
IHE Delft PhD Thesis Ser |
|
IHE Delft PhD Thesis Ser
|
| Contents |
Cover; Half Title; Title Page; Copyright Page; Dedication; Acknowledgements; Summary; Samenvatting; Table of Contents; 1: General introduction; 1.1 Wetland ecosystem services; 1.2 Rehabilitation and restoration of wetland ecosystem services; 1.3 Significance of the study; 1.4 Hypotheses of the study; 1.5 Research objectives; 2: Effects of river discharge and land use and land cover (LULC) on water quality dynamics in Migina catchment, Rwanda; Abstract; 2.1 Introduction; 2.2 Material and Methods; 2.2.1 Study area; 2.2.2 Field sampling design; 2.2.3 Data collection; 2.3. Results |
|
2.3.1 Rainfall, discharge and water quality in three Migina sub-catchments2.3.2 Rainfall, discharge and water quality in Munyazi sub-catchment; 2.3.3 Water quality as affected by season and LULC in 16 reaches of Munyazi; 2.4 Discussion; 2.5. Conclusion; 2.6 Acknowledgements; 3: Effects of agricultural land use on sediment and nutrient retention in valley-bottom wetlands of Migina catchment, southern Rwanda; Abstract; 3.1 Introduction; 3.2 Material and Methods; 3.2.1 Study area and period; 3.2.2 Data collection; 3.3 Results |
|
3.3.1 Reach characteristics, population density, land use and reach classification3.3.2 Rainfall, water, TSS, TP and TN yields at Rwabuye gauging station; 3.3.3 Net yield of water, TSS, TP and TN in relation to land use categories; 3.3.4 Water, sediment and nutrient yield in relation to land use and discharge; 3.3.5 Water, sediment and nutrient yield and reach characteristics; 3.4 Discussion; 3.5 Conclusion; 3.6 Acknowledgements; 4: Mesocosm studies on the effects of conversion of wetlands to rice and fish farming on water quality in valley bottoms of the Migina catchment, southern Rwanda |
|
Abstract4.1. Introduction; 4.2. Material and Methods; 4.2.1. Study area and period; 4.2.2. Experimental setup; 4.2.3. Data collection; 4.3. Results; 4.3.1. Land use practices; 4.3.2. Hydrological processes; 4.3.3. Biomass production; 4.3.4. Water quality; 4.4. Discussion; 4.5. Conclusion; 4.6 Acknowledgements; 5: Mesocosm studies on the impacts of conversion of wetlands into fish and rice farming on sediment and nutrient loads to surface water; Abstract; 5.1 Introduction; 5.2. Material and Methods; 5.2.1 Study area and period; 5.2.2 Experimental setup; 5.2.3 Data collection; 5.3. Results |
|
5.3.1. Nutrient analysis5.3.2. Seasonal variation in sediment and nutrient loads; 5.3.3 Differences among LULC types; 5.3.4 Retention of sediment, nitrogen and phosphorus; 5.4 Discussion; 5.5 Conclusion; 6: Effects of wetland conversion into farming on water quality, sediment and nutrient retention -- synthesis, conclusions and recommendations; 6.1 Synthesis of the findings; 6.2 Scale issues; 6.3 Surface and groundwater pathways; 6.4 Impact of farming; 6.5 Regional implications; 6.6 Implications to future economic development and climate change; 6.7 Recommendations for future research |
| Summary |
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 |
| Notes |
7: References |
|
Print version record |
| Subject |
Water quality -- Measurement.
|
|
Wetland management.
|
|
SCIENCE -- Environmental Science.
|
|
TECHNOLOGY -- Engineering -- Civil.
|
|
Water quality -- Measurement
|
|
Wetland management
|
| Form |
Electronic book
|
| ISBN |
9781000025606 |
|
1000025608 |
|
9781003016106 |
|
1003016103 |
|
9781000025682 |
|
1000025683 |
|
9781000025644 |
|
1000025640 |
|
