Discussed in this paper are results of the study that was conducted as part of the process of compiling Malawi’s State of the Environment and Outlook Report for the year 2010. The status of the country’s economy and...Discussed in this paper are results of the study that was conducted as part of the process of compiling Malawi’s State of the Environment and Outlook Report for the year 2010. The status of the country’s economy and the nature of governance were identified as critical drivers, i.e., “critical uncertainties”, in determining the future state of the environment in Malawi. Four environmental scenarios were developed, namely: Scenario 1: “Mkaka ndi Uchi”, a combination of good economy and good governance;Scenario 2: “Penda Penda”, a combination of poor economy and good governance;Scenario 3: “Wafa Wafa”, a combination of poor economy and poor governance;and Scenario 4: “Chonchobe/Ndawonera Momwemo”, a combination of good economy and poor governance. Each of the four scenarios will be uniquely influenced by the prevailing economic and governance situation in the country, and hence impact differently on Malawi’s environment. Economy and Governance were selected as critical determinants out of seven key environmental drivers: demography, governance, social change, economy, environment and climate change, technology, and culture and tradition. From the above listed scenarios, it is only Scenario 1, Mkaka ndi Uchi, which will result in a prosperous Malawi while the rest portend the prevalence of a chaotic situation in the country, more so Scenario 3, the Wafa Wafa scenario.展开更多
This paper discusses a procedure that was developed to delineate potential fishing grounds in Lake Malawi using data on chlorophyll-a concentration derived from Moderate-resolution Imaging Spectroradiometer (MODIS/AQU...This paper discusses a procedure that was developed to delineate potential fishing grounds in Lake Malawi using data on chlorophyll-a concentration derived from Moderate-resolution Imaging Spectroradiometer (MODIS/AQUA) in combination with lake surface temperature (LST) data obtained from Advanced Very High Resolution Radiometer (AVHRR) and MODIS/Terra satellite sensors. The paper draws from findings of studies [1,2] on development of algorithms for estimating chlorophyll-a and lake surface temperature in Lake Malawi from satellite imagery, respectively. To estimate chlorophyll concentration (a proxy for phytoplankton) in Lake Malawi using data from MODIS satellite imagery, in situ measurements of chlorophyll concentration were conducted at three selected sampling stations over the southeastern arm of Lake Malawi concurrent with satellite image acquisitions. These were regressed on chlorophyll-a concentration values obtained from Ocean Color (MODIS/AQUA) Data using SeaWIFS Data Analysis System (SeaDAS) software. From this, an equation for estimating chlorophyll-a concentration in Lake Malawi from MODIS satellite imagery was developed and used for mapping the spatial distribution of chlorophyll-a concentration in the lake. Since Lake Malawi is an oligotrophic lake, with an average value of chlorophyll concentration of 1 μg/L, areas in the lake with relatively high chlorophyll-a concentration were identified as potential locations for the development of the fishery industry. Estimation of lake surface temperature using satellite imagery involved two main activities. Firstly, in situ measurements of lake surface temperature were conducted at the three selected sampling stations over Lake Malawi concurrent with satellite image acquisitions. The second activity involved downloading and processing AVHRR and MODIS/Terra satellite imagery. AVHRR data covered the period September 1997 to February 1998 whereas MODIS/Terra data covered the period May to November, 2006. Both MODIS Land Surface Temperature (MOD11A1) and Ocean Color Sea Surface Temperature (SST) were downloaded from EOS Gateway website and processed into lake surface temperature. Two glass thermometers were used to measure temperature directly from the lake surface at a depth of 0 - 7.0 cm (i.e., skin temperature) and the average of the two readings was recorded as the lake surface temperature at a particular sampling station. Observed temperatures were regressed on remotely sensed data. ER Mapper was employed in drawing maps showing the distribution of lake surface temperature using the regression equation that was developed. Upwelling and downwelling zones were demarcated from lake surface temperature maps. Upwelling zones were identified as areas with a high potential for the development of the fishery industry because of their association with primary productivity. Using a simple overlay technique, data from both the spatial and temporal distribution of chlorophyll-a and lake surface temperature were used to delineate potential fishing grounds in Lake Malawi. The zone extending from Salima up to the northern part of Nkhotakota and the area on the northeastern tip of Lake Malawi were identified as areas of high primary productivity and therefore potential fishing grounds. These areas generally exhibit persistent cool surface waters, indicative of upwelling;and have relatively abundant phytoplankton.展开更多
Changes in land use and land cover (LULC) in the drainage basin of Lake Malawi over the period 1982-2005 were estimated from satellite imagery, and possible relationships were evaluated among the four major land-cover...Changes in land use and land cover (LULC) in the drainage basin of Lake Malawi over the period 1982-2005 were estimated from satellite imagery, and possible relationships were evaluated among the four major land-cover classes: cropland, forest, water, and savanna/shrub/woodland. AVHRR and MODIS sensors gave different values of areal extent of the four classes, limiting the feasibility of establishing consistent temporal trends over the entire period of the study, but forest land showed the least change among three land cover types, and extent of water bodies remained virtually unaltered over the period. AVHRR results show that cropland was mainly derived from savanna/shrub/woodland, which declined by almost 90% over the period 1982-1995.展开更多
文摘Discussed in this paper are results of the study that was conducted as part of the process of compiling Malawi’s State of the Environment and Outlook Report for the year 2010. The status of the country’s economy and the nature of governance were identified as critical drivers, i.e., “critical uncertainties”, in determining the future state of the environment in Malawi. Four environmental scenarios were developed, namely: Scenario 1: “Mkaka ndi Uchi”, a combination of good economy and good governance;Scenario 2: “Penda Penda”, a combination of poor economy and good governance;Scenario 3: “Wafa Wafa”, a combination of poor economy and poor governance;and Scenario 4: “Chonchobe/Ndawonera Momwemo”, a combination of good economy and poor governance. Each of the four scenarios will be uniquely influenced by the prevailing economic and governance situation in the country, and hence impact differently on Malawi’s environment. Economy and Governance were selected as critical determinants out of seven key environmental drivers: demography, governance, social change, economy, environment and climate change, technology, and culture and tradition. From the above listed scenarios, it is only Scenario 1, Mkaka ndi Uchi, which will result in a prosperous Malawi while the rest portend the prevalence of a chaotic situation in the country, more so Scenario 3, the Wafa Wafa scenario.
文摘This paper discusses a procedure that was developed to delineate potential fishing grounds in Lake Malawi using data on chlorophyll-a concentration derived from Moderate-resolution Imaging Spectroradiometer (MODIS/AQUA) in combination with lake surface temperature (LST) data obtained from Advanced Very High Resolution Radiometer (AVHRR) and MODIS/Terra satellite sensors. The paper draws from findings of studies [1,2] on development of algorithms for estimating chlorophyll-a and lake surface temperature in Lake Malawi from satellite imagery, respectively. To estimate chlorophyll concentration (a proxy for phytoplankton) in Lake Malawi using data from MODIS satellite imagery, in situ measurements of chlorophyll concentration were conducted at three selected sampling stations over the southeastern arm of Lake Malawi concurrent with satellite image acquisitions. These were regressed on chlorophyll-a concentration values obtained from Ocean Color (MODIS/AQUA) Data using SeaWIFS Data Analysis System (SeaDAS) software. From this, an equation for estimating chlorophyll-a concentration in Lake Malawi from MODIS satellite imagery was developed and used for mapping the spatial distribution of chlorophyll-a concentration in the lake. Since Lake Malawi is an oligotrophic lake, with an average value of chlorophyll concentration of 1 μg/L, areas in the lake with relatively high chlorophyll-a concentration were identified as potential locations for the development of the fishery industry. Estimation of lake surface temperature using satellite imagery involved two main activities. Firstly, in situ measurements of lake surface temperature were conducted at the three selected sampling stations over Lake Malawi concurrent with satellite image acquisitions. The second activity involved downloading and processing AVHRR and MODIS/Terra satellite imagery. AVHRR data covered the period September 1997 to February 1998 whereas MODIS/Terra data covered the period May to November, 2006. Both MODIS Land Surface Temperature (MOD11A1) and Ocean Color Sea Surface Temperature (SST) were downloaded from EOS Gateway website and processed into lake surface temperature. Two glass thermometers were used to measure temperature directly from the lake surface at a depth of 0 - 7.0 cm (i.e., skin temperature) and the average of the two readings was recorded as the lake surface temperature at a particular sampling station. Observed temperatures were regressed on remotely sensed data. ER Mapper was employed in drawing maps showing the distribution of lake surface temperature using the regression equation that was developed. Upwelling and downwelling zones were demarcated from lake surface temperature maps. Upwelling zones were identified as areas with a high potential for the development of the fishery industry because of their association with primary productivity. Using a simple overlay technique, data from both the spatial and temporal distribution of chlorophyll-a and lake surface temperature were used to delineate potential fishing grounds in Lake Malawi. The zone extending from Salima up to the northern part of Nkhotakota and the area on the northeastern tip of Lake Malawi were identified as areas of high primary productivity and therefore potential fishing grounds. These areas generally exhibit persistent cool surface waters, indicative of upwelling;and have relatively abundant phytoplankton.
文摘Changes in land use and land cover (LULC) in the drainage basin of Lake Malawi over the period 1982-2005 were estimated from satellite imagery, and possible relationships were evaluated among the four major land-cover classes: cropland, forest, water, and savanna/shrub/woodland. AVHRR and MODIS sensors gave different values of areal extent of the four classes, limiting the feasibility of establishing consistent temporal trends over the entire period of the study, but forest land showed the least change among three land cover types, and extent of water bodies remained virtually unaltered over the period. AVHRR results show that cropland was mainly derived from savanna/shrub/woodland, which declined by almost 90% over the period 1982-1995.
