Using Earth Observation Data for Monitoring River Basins

Transcription

1 Using Earth Observation Data for Monitoring River Basins The NBI Experience By Milly Mbuliro GIS/ Remote Sensing Specialist Nile Basin Initiative Secretariat NBDF, 23 rd -25 th October, Kigali Convention Center, Kigali, Rwanda

2 NBI: Overview The Nile Basin Initiative (NBI) is a regional intergovernmental Partnership among 10 countries. Objective is to Promote sustainable utilization of the Nile Basin resources. It is our Mandate to Monitor the status of the basin to promote informed evidence - based decision making SOUTH SUDAN D R CONGO UGANDA RWANDA BURUNDI EGYPT SUDAN ETHIOPIA KENYA TANZANIA

3 The Nile Basin The Nile cuts across diverse climatic zones (humid to arid conditions) Spatial and Temporal variation in its processes. Highest population growth rates in the region. Each riparian state has development master plans ( irrigation master plan, Energy master plan etc Leading to increased need and pressure on the finite resources. Faces environmentally related challenges such as floods, Land degradation, surface water pollution, sediment load and others

4 Fundamental questions Is the Nile basin water Secure? Is Climate change a real threat to the Nile basin region? How much water is available to meet the demand Are our resources sustainable? What will be the status years after and how was it years before? Is there any potential for development? Untapped potential You can not manage what you can not measure; That is why we monitor

5 NBI Response The NBI informs and provides a platform for dialogue over such issues through Strategic Analysis and group discussions Preparation of periodic state of River Nile Basin Reports, first one in 2012, next issue in 2018 Under the Hydro-Met project, the NBI aims to set up a regionally recognized monitoring system to capture and store readings of key climatic variable. Design stage, agreed upon by countries already completed, looking for funds to implement the regional monitoring System in phases The proposed regional system comprises of ground measurements and satellite based measurements

6 Basin Monitoring NBI promotes good data management, data sharing and data communication to resource managers in a consistent, harmonized and understandable way Variables monitored include Rainfall, Evapotranspiration, Relative Humidity, Land and Air Temperature, Water levels, Soil erosion Vulnerability, Land-cover /use change, Seasonal Variation of Wetland areas, Soil Moisture, Vegetation cover and socio economic indicators among others.

7 Nile Basin Rainfall Monitored by both observed and satellite data Data Products are mainly TRMM 3B43v7 monthly product and the 3B42 daily product. Other rainfall data products include CRU_TS, from the Climatic research unit (includes rain-guage data Chirps, RFE from the NOAA. A comparison of how the different products estimate rainfal over the different subbasins was made Analysis to compare with ground measurements is ongoing

8 Nile Basin Rainfall-Annual Find more in the Nile Basin Water Resources Atlas

9 Nile Basin Rainfall- Comparative assessment Baro- Akobbo- Sobat Subbasin Lake Victoria Subbasin

10 Nile Basin Rainfall- Comparative assessment Bahr el Jebel Subbasin Lake Albert Subbasin

11 Nile Basin Rainfall- Comparative assessment Blue Nile Subbasin Main Nile Subbasin

12 Actual Evapotranspiration ET is an important component of the water balance Is the only consumer of water Water balance models were used to estimate ET as the remainder after determining all other balance components Now, Satellite based techniques have emerged NBI has generated Actual Evapotransipiration estimates over Nile Basin Countries based on MOD16ET Spatial resolution;1km cell size Temporal resolution is 8 days, monthly and annual

13 Actual Evapotranspiration The data shows Temporal and spatial variation over the Nile Basin. ET accounts for 87% of basin rainfall There is variation even at sub-basin level Highest in the Nile Equatorial lakes region due to moisture availability

14 Sample analyses ET: ETo ratio gives an indication of moisture availability Highest ET/ETo ratio occurs in the Lake Albert Sub basin and the Sudd area Lowest ET:ETo is found in the Main Nile and Tekeze Atbara Subbasin which are mostly dry. Ratio of ET:P shows the conversion rate of available moisture to evapotranspiration When ratio is less than 1 there is potential for generation of runoff or recharge ground water When ratio is more than 1, all the rainfall and water coming in through the river is lost as AET

15 Products 11 Long Term and Seasonal Variation of Wetlands. Small water body mapping in the Sudd region Based on Sentineldata Uses soil moisture retrieval technique

16 Other water quality indicators that can be measured from satellite data include: TDS Lake Surface Temperature And others White regions show no data From this analysis, point source contamination can be identified

17 Flood mapping Flood prone areas Threshold classification Historical flood mapping Data requirements ENVISAT ASAR data Erosion potential / Vulnerability Soil erosion Potential Hot Spot Detection Data Requirements NOAA RFE Rainfall data FAO Soils SRTM DEM ESA GlobCover Landcover

18 Knowledge Products Nile Basin Water Resources Atlas State of River Nile Basin Report MSIOA reports Understanding Nile Basin Hydrology: Mapping Actual evapo-transipiration over Nile basin countries Visit for more publications

19 Implications for River Basin management You can not manage what you can not measure or monitor. In view of all country development master plans, monitoring is a must Satellite data has been recognised as a feasible technique for monitoring a wide range of earth processes. Satellite data and techniques keep evolving, so should resource managers. River basins like the Nile basin with ungauged catchments/limited ground observations need EO data. Data management and sharing are key components for river basin management and this calls for regional cooperation. NBI offers such a platform where transboundary data can be shared. NBI has designed a regional hydromet system (with a component on EO data) with all key stakeholders consulted, agreed upon by countries and awaits implementation. Use of Earth Observation data is encouraged to compliment ground observations for River basin monitoring/management

20 THANK YOU Milly Mbuliro