3 Methodology

2METHODOLOGY

2.1 OVERVIEW OF FFR METHODOLOGY

The methodology to determine the connectivity and free-flowing status of rivers (or Free-flowing river assessment; FRA) is based on a global methodology developed by Grill. A Free-flowing River Assessment comprises six distinct steps (see Figure 3): First, an integrated definition of FFRs was developed according to multiple aspects of connectivity (step 1). Second, the major pressure factors that influence river connectivity were identified (step 2) using an extensive literature review, and data was collated for each factor. The six pressure factors that were identified include: (a) river fragmentation; (b) flow regulation; (c) sediment trapping; (d) water consumption; (e) road construction; and (f) urbanization.

Next, proxy indicators were calculated (step 3) for each factor using data from available global remote sensing products, other data compilations, or numerical model outputs such as discharge simulations (see Table 1). The indicators that were chosen are expected to have a substantial influence on connectivity and can be generated using robust global data sets of sufficient quality and consistency between countries and regions. All indicators were calculated for every river reach of the river network. A river reach is defined as the smallest A element in the river network and is the line segment between confluences.

Grill et al. adjusted the weighting of each pressure indicator adjusted iteratively in a set of scenarios using different thresholds guided by literature reviews and expert judgement. These scenarios were benchmarked by comparing the resulting FFRs against reported FFRs compiled from literature resources and expert inputs. The final selection of weightings was applied to a multi-criteria average calculation (step 4) to derive the Connectivity Status Index (CSI) for every river reach (step 5).

Free-flowing rivers definition based on connectivity

Calculation of proxy indicators

CSI (%)

100 99-95 94-90 89-80 79-60 <60

Connectivity Status Index (CSI) 1

3

5 2

4

6

Selection of pressure factors related to definition

Application of weighting model

Application of threshold

Yes

River reach CSI status above threshold (CSI > 95%) No

River reach with good connectivity status (above CSI threshold) River reach impacted (below CSI threshold)

Entire river before threshold from source to outlet?

Yes Free-flowing river

Figure 3: Conceptual overview of methodology by Grill et al.

The CSI ranges from 0% to 100%, the latter indicating full connectivity. Only river reaches with a CSI greater than 95% were considered as having ‘good connectivity status’ while river reaches below 95% were classified as impacted (step 6). Finally, river reaches were aggregated into rivers with contiguous flow paths from the source to the river outlet. If a river is above the CSI threshold of 95% across its entire length it is declared to be a FFR. Otherwise, the river as a whole is declared not free-flowing, but it can maintain a mix of stretches with ‘good connectivity status’ and stretches that are impacted.

Pressure Factor Pressure Indicator

River Fragmentation DOF

Flow Regulation DOR Description

Connectivity aspect affected

Degree of Fragmentation Longitudinal

Degree of Regulation Lateral, temporal

Sediment Trapping SED

Sediment Trapping Index Longitudinal, lateral, vertical Source

HydroSHEDS (Lehner, Verdin and Jarvis, 2008); GRanD v1.1 (Lehner et al., 2011); GOOD2 v1 (Mulligan et al., 2009); WWF, Greater Mekong Program

HydroSHEDS (Lehner, Verdin and Jarvis, 2008); GRanD v1.1 (Lehner et al., 2011); GOOD2 v1 (Mulligan et al., 2009); HydroLAKES, v1.0 (Messager et al., 2016); WWF, Greater Mekong Program

Erosion map (Borrelli et al., 2017); HydroSHEDS; (Lehner, Verdin and Jarvis, 2008); GRanD v1.1; (Lehner et al., 2011); GOOD2 v1 (Mulligan et al., 2009); HydroLAKES, v1.0 (Messager et al., 2016); WWF, Greater Mekong Program.

Water consumption USE Consumptive water use (abstracted from rivers)

Longitudinal, Lateral, vertical, temporal WaterGAP, v2.2 as of 2014 (Alcamo et al., 2003; Döll, Kaspar and Lehner, 2003); HydroSHEDS, (Lehner, Verdin and Jarvis, 2008)

Infrastructure development in riparian and floodplain areas RDD Road density

URD Nightlight intensity in urban areas

Lateral, longitudinal

Lateral

Table 1:Pressure indicators and their data sources of the global FRA (from Grill et al. 2019). GRIP v3; (Meijer et al., 2018)

DMSP-OLS v4 Doll, (Doll, 2008) Modis-derived urban areas by (Schneider, Friedl and Potere, 2009)

2.2 LOCAL ADAPTATION OF

FFR METHODOLOGY AND DATA SOURCES USED

As a first step, the existing global data and methodology was reviewed and then discussed with local experts and stakeholders in order to determine possible refinements and enhancements to better represent the local context. For this a one-day workshop was arranged with the Union Government’s cross-ministerial water specialists group and officials from different concerned departments and ministries. The approach and data were also discussed with key decision makers from the Irrigation and Water Utilization Management Department (Ministry of Agriculture, Livestock and Irrigation) and the Directorate of Water Resources and Improvement of River Systems (Ministry of Transport). Moreover, a technical seminar was organized at Yangon Technological University to strengthen the local capacity and share the available resources with academic institutes to contribute further research which, in turn, will help to provide improved data and supporting information for the decision making processes.

Stakeholders stressed the need to update the barrier database because a number of dams relevant for the assessment were missing from the global database, and potential future development of river infrastructure, in particular hydropower dams, is considered a key factor for change in river connectivity.

The global dataset on dams was therefore complemented with data from a national database, with information from reports, and information on individual irrigation dams received from the Irrigation and Water Utilization Management Department. Other variables for defining pressure indicators, such as sediment extractions, roads, irrigation water, or urban areas could not be updated within the framework of this study. For these the analysis therefore relied on global data described in Table 1.

We defined two scenarios of hydropower development and calculated the Free-flowing River Status, the Connectivity Status Index (CSI), and the Dominant Pressure Index (DOM). Subsequently we produced summary statistics for the different river length classes, comparing the results of the two scenarios.

2.2.1 DAM DATABASE

Based on feedback from stakeholders, a critical step was updating the dams data to include a more comprehensive set of data for the region of analysis. The global dam database was compared against a GIS database of existing and proposed hydropower projects over 10 MW capacity compiled by the International Finance Cooperation (IFC, 2019) within the framework of the Strategic Environmental Assessment (SEA) of the Myanmar Hydropower sector (IFC, 2018), with information from the SEA Baseline Documents (Lazarus et al., 2019), and against with information obtained from the Irrigation and Water Utilization Management Department of the Ministry of Agriculture, Livestock and Irrigation.

After complementing and harmonising these data sources, 208 barriers were identified and used in this analysis (Annex 7.2, Table 4). These include 133 existing, 6 under construction and 69 planned dams. A purpose was identified for 106 of these barriers as follows: 74 for hydropower, 18 for irrigation, 13 for multiple purposes and 1 for water supply.

2.2.2 HYDROLOGICAL NETWORK

The inventory of rivers and streams from HydroSHEDS (Lehner, Verdin and Jarvis, 2008) was used for the analysis of river connectivity in Myanmar. We selected the rivers within the boundaries of Myanmar and added rivers upstream and downstream of Myanmar to the network because dam impacts from locations outside the country can have effects within Myanmar (e.g. fragmentation and flow regulation). All existing pressure factors within and outside of the country were therefore considered when establishing the current situation.

These transboundary rivers included the Irrawaddy, Salween, Mekong and Ganges/Brahmaputra basins, with parts of the river basins outside of Myanmar. The river network included a total of 161,000 km of rivers (defined as streams with an average discharge of larger than 1 cubic meter per second), of which 115,000 km flow within Myanmar.

Figure 4: Overview of existing and planned dams used in the region of analysis.

2.3 SITUATION / SCENARIOS

For this report we analysed the following two states of dam development:

A The current situation of FFR in Myanmar and in areas upstream or downstream of Myanmar (existing dams and under construction)

B The situation of FFR under the assumption that proposed large dam projects (>10MW) are developed (existing, under construction, and planned dams). This scenario is analogous with the “business as usual” scenario laid out in the SEA (IFC, 2018). The scenario assumes that proposed and identified projects will be developed on a project-by-project basis. We did not consider planned dam development outside of the country that may cause impacts within Myanmar.

The results are presented in maps and analysed in terms of number of FFRs, length of FFR, the connectivity status index of rivers and the dominant pressure on the different types of connectivity (described in Chapter 1, Figure 1).