Indicator 6.4.2 Level of water stress: freshwater withdrawal as a proportion of available freshwater resources

Goal 6: Ensure availability and sustainable management of water and sanitation for all

Target 6.4: By 2030, substantially increase water-use efficiency across all sectors and ensure sustainable withdrawals and supply of freshwater to address water scarcity and substantially reduce the number of people

suffering from water scarcity

Indicator 6.4.2: Level of water stress: freshwater withdrawal as a proportion of available freshwater resources

November 2021

6.4.1, 6.1.1, 6.3.1, 6.6.1, 6.5.1, 2.4.1, 15.3.1, 1.5.1, 11.5.1

Ministry of Water and Environment

Ivan Biiza

Water and Environment Sector Liaison Department

Economist

+256 782 848455

P.O Box 20026, Kampala

Ivan.biiza@mwe.go.ug

Definition:

The level of water stress: freshwater withdrawal as a proportion of available freshwater resources is the ratio between total freshwater withdrawn by all major sectors and total renewable freshwater resources, after taking into account environmental flow requirements. Main sectors, as defined by ISIC standards, include agriculture; forestry and fishing; manufacturing; electricity industry; and services. This indicator is also known as water withdrawal intensity.

The indicator is defined as the ratio between total freshwater withdrawn by all economic activities as categorized by the ISIC and the total renewable freshwater resources, after having taken into account environmental water requirements which include water withdrawals by all economic activities, focusing on agriculture, manufacturing, electricity, and water collection, treatment and supply.

Concepts:

This indicator provides an estimate of pressure by all sectors on the country’s renewable freshwater resources. A low level of water stress indicates a situation where the combined withdrawal by all sectors is marginal in relation to the resources, and has therefore little potential impact on the sustainability of the resources or on the potential competition between users. A high level of water stress indicates a situation where the combined withdrawal by all sectors represents a substantial share of the total renewable freshwater resources, with potentially larger impacts on the sustainability of the resources and potential situations of conflicts and competition between users.

Total Renewable Fresh Water Resources (TRWR) are expressed as the sum of internal and external renewable water resources. The terms “water resources” and “water withdrawal” are understood here as freshwater resources and freshwater withdrawal.

Internal renewable water resources are defined as the long-term average annual flow of rivers and recharge of groundwater for a given country generated from endogenous precipitation. External renewable water resources refer to the flows of water entering the country, taking into consideration the quantity of flows reserved to upstream and downstream countries through agreements or treaties.

Total Fresh Water Withdrawal (TFWW) is the volume of freshwater extracted from its source (rivers, lakes, aquifers) for agriculture, industries and services. It is estimated at the country level for the following three main sectors: agriculture, services (including domestic water withdrawal) and industries (including cooling of thermoelectric plants). Freshwater withdrawal includes fossil groundwater. It does not include non-conventional water, i.e. direct use of treated wastewater, direct use of agricultural drainage water and desalinated water.

Environmental Flow Requirements (EFR) are defined as the quantity and timing of freshwater flows and levels necessary to sustain aquatic ecosystems, which, in turn, support human cultures, economies, sustainable livelihoods, and wellbeing. Water quality and also the resulting ecosystem services are excluded from this formulation which is confined to water volumes. This does not imply that quality and the support to societies which are dependent on environmental flows are not important and should not be taken care of. Methods of computation of EFR are extremely variable and range from global estimates to comprehensive assessments for river reaches. For the purpose of the SDG indicator, water volumes can be expressed in the same units as the TFWW, and then as percentages of the available water resources

Percent

• The System of Environmental-Economic Accounting for Water

• The World Census of Agriculture 2020: WCA (Volume 1), for irrigation definitions

• International Standard Industry Classification (ISIC)

Administrative data

Data collection is done by the Ministry through the Water Resources Management directorate which sets up deconcentrated technical structure in the respective regions of Uganda called Water Management Zones. It is through the Technical officers in these respective Water Management Zones that the monthly data is collected and sent through to the Centre where the eventual validation, packaging and analysis is done by the SDG task team at the Ministry headquarters. The publication is done on an Annual basis through the Annual Sector Performance Report.

Monthly

Annually

Ministry of Water and Environment.

Ministry of Water and Environment

Ministry of Water and Environment has the mandate to ensure that the Water resources in the country are managed appropriately to enable the efficient use of water for the various critical responsibilities.

The purpose of this indicator is to show the degree to which water resources are being exploited to meet the country’s water demand. It measures the country’s pressure on its water resources and therefore the challenge on the sustainability of its water use. It tracks progress in regard to “withdrawals and supply of freshwater to address water scarcity”, That to say; the environmental component of target 6.4.

This indicator provides an estimate of pressure by all sectors on the country’s renewable freshwater resources. The indicator shows the extent to which water resources are already used, and signals the importance of effective supply and demand management policies. It indicates the likelihood of increasing competition and conflict between different water uses and users in a situation of increasing water scarcity. Increased water stress, shown by an increase in the value of the indicator, has potentially negative effects on the sustainability of the natural resources and on economic development. On the other hand, low values of the indicator indicate that water does not represent a particular challenge for economic development and sustainability.

Freshwater withdrawal as a percentage of renewable freshwater resources is a good indicator of pressure on limited water resources, one of the most important natural resources. However, it only partially addresses the issues related to sustainable water management.

Trends in freshwater withdrawal show relatively slow patterns of change. Usually, three-five years are a minimum frequency to be able to detect significant changes, as it is unlikely that the indicator would show meaningful variations from one year to the other.

Estimation of water withdrawal by sector may represent a limitation to the computation of the indicator. In Uganda, publication of water withdrawal data is not on a regular basis.

There is no universally agreed method for the computation of incoming freshwater flows originating outside of a country’s borders. Nor is there any standard method to account for return flows, the part of the water withdrawn from its source and which flows back to the river system after use.

In Uganda where return flow represents a substantial part of water withdrawal, the indicator tends to underestimate available water and therefore overestimate the level of water stress.

Computation Method:

The indicator is computed as the total freshwater withdrawn (TFWW) divided by the difference between the total renewable freshwater resources (TRWR) and the environmental flow requirements (EFR), multiplied by 100. All variables are expressed in km3/year (109 m3/year).

Stress (%) = TFWW / (TRWR - EFR) * 100%

Following the international standard, the threshold of 25% has been identified as the upper limit for a full and unconditional safety of water stress.

That means on one hand, that values below 25% can be considered safe in any instance (no stress); on the other, that values above 25% should be regarded as potentially and increasingly problematic, and should be qualified and/ or reduced.

Above 25% of water stress, four classes have been identified to signal different levels of stress severity:

• No Stress <25%

• Low 25% - 50%

• Medium 50% - 75%

• High 75-100%

• Critical >100%

Data on Environmental flow requirements is re-updated only when detailed methodology and metadata is re-provided and when consistency in the values is needed.

Data validation is done in a number of steps:

1. Review of the data collected at every Water Management Zone level.
2. Data is reviewed by the respective SDG task team at the Ministry.
3. Data is also validated by the consultant preparing the Annual Performance Report.

FAO’s AQUASTAT team provides continued guidance to the countries thought the National Correspondents during the data collection time to ensure data is duly and timely compiled.

During the reporting process, the data is collected primarily from the respective data sources and submitted to the Ministry respective Headquarter office. It is at this stage that the experts analyses and clean up the data which is later publically produced in the Annual Performance report.

FAO is responsible for the quality of the internal statistical processes used to compile the published datasets. The Ministry of Water and Environment through the respective regional structures created at all the respective levels goes ahead to ensure timely capture of the data through the respective approved data collection tools. It is through this elaborate but specific process that the data captured is cleaned and reviewed in case of anomalies before final submission to the Headquarters for final analysis and interpretation in order to be captured in the Annual Performance report which is in turn shared with the Uganda Bureau of Statistics for capture in the computation of the respective National indicators.

Overall evaluation of data quality is based on standard quality criteria and follows FAO’s SQAF. It also includes:

• Time-series coherency check done by running an R-script to compare reported data with those corresponding to previous years.

Data needed for the indicator are collected through the respective Water Management Zones which are clearly covering all the different regions of the country.

Disaggregation:

Data can be disaggregated by source and economic activity. The disaggregation of data to the basin level, supported by geo-referencing.

Water resources and withdrawals are estimated or measured at the level of appropriate hydrological units (river basins, aquifers).

For national estimates incoming freshwater is counted as being part of the country’s available freshwater resources, while global estimates can only be done by adding up the internal renewable freshwater resources (water generated within the country) of all countries in order to avoid double counting. Moreover, external freshwater resources are

computed according to treaties, if present, which may lead to different values with respect to the actual freshwater resources assessed through hydrology.

References:

Water and Environment Annual Performance Report.

Monthly Performance Progress reports