Abstract:In the past few decades, there have been extensive efforts on measuring sustainability. One example is the development of assessment tools based on sustainability indicators. Several individuals and organisations have suggested various indices for assessing sustainability. This paper focuses on the review of water sustainability assessment using the indicator-based approach. It discusses major definitions of sustainable development that have been proposed and more specific concepts of sustainability based on sustainability principles and criteria. It then proceeds with the review of existing definitions, principles and guidelines on sustainable water resource management. The paper then explores elements of indicatorbased water sustainability assessment. These elements include the selection of components and indicators, obtaining sub-index values, weighting schemes for components and indicators, aggregation of components and indicators, robustness analysis of the index, and interpretation of the final index value. These six elements are explored considering four existing water sustainability indices and two other sustainability indices that are thought to be useful for the development and use of water sustainability indices.The review presented in this paper on indicator-based water sustainability assessment can provide significant inputs to water stakeholders worldwide for using existing indices, for customising existing indices for their applications, and for developing new water sustainability indices. These indices can provide information on current conditions of water resources, including identifying all factors contributing to the improvement of water resources. This information can be used to communicate the current status of existing water resources to the wider community. Also, the water sustainability indices can be used to assist decision makers to prioritise issues, challenges and programs related to water resource management.

Sustainable water resources management is essential since it ensures the integration of social, economical and environmental issues into all stages of water resources management. The development and application of water sustainability indices to achieve sustainable water management has been successfully done in the last few years. Although existing water sustainability indices have successfully provided information on current conditions of water resources and prioritised water related issues, they have been developed for specific case study areas. This study therefore aims at developing a water sustainability index for West Java, Indonesia. The overall steps for developing the index include developing a conceptual framework, application of Delphi technique to finalise the components/indicators of the index, applying the index to case studies and robustness analysis of the index. This paper, which is the first in a two-part series, discusses the first step, namely developing the conceptual framework of the West Java Water Sustainability Index (WJWSI). It outlines the criteria for identifying the initial set of components/indicators and based on those criteria, a detailed justification for selecting each component and indicator is also presented. The second paper of the series presents the application of Delphi technique to finalise the framework of WJWSI based on feedback from selected stakeholders. The remaining steps of developing WJWSI will be undertaken in the future.

ABSTRAKSungai Cikapundung merupakan anak sungai DAS Citarum Hulu yang digunakan untuk sumber air baku air minum, irigasi dan perikanan di Kota Bandung. Sungai Cikapundung yang melewati Kabupaten Bandung Barat, Kota Bandung dan Kabupaten Bandung berpotensi tercemar oleh limbah dari sektor domestik. Namun saat ini belum ada informasi mengenai beban pencemar terhadap Sungai Cikapundung dari sektor domestik. Oleh karena itu perlu dilakukan penelitian dengan tujuan untuk mengukur tingkat pencemaran di Sungai Cikapundung dengan menghitung, status mutu air, potensi beban pencemaran sektor domestik. Status mutu air ditentukan dengan menggunakan metode indeks pencemar dan potensi beban pencemaran Sungai Cikapundung dihitung menggunakan pendekatan faktor emisi limbah domestik. Berdasarkan hasil perhitungan menunjukan bahwa Sungai Cikapundung pada tahun 2016 memiliki kriteria mutu air cemar sedang pada bulan kering dan cemar ringan di bulan basah. Sungai Cikapundung telahtercemar limbah domestik berdasarkan hasil perhitungan beban pencemar mengalami kenaikan seiring dengan meningkatnya jumlah penduduk pada tahun 2021 oleh 25.383,89 Kg/ hari TSS, 17.537,96 kg/hari BOD, 18.461,01 kg/hari COD, 889,97 kg/hari N-Total dan 96,92 Kg/hari P-Total.Kata kunci: Beban Pencemar, Domestik Cikapundung, Kualitas AirABSTRACTCikapundung river is the sub river of upper Citarum River which was used by the people in Bandung city as a raw water for drinking water, irrigation and fishery. Cikapundung river that passes through many districts of Bandung have a great potential of being polluted by from domestic waste. This condition will affects the water quality of Cikapundung water. Having this condition, the urgency of conducting the research for measure the polution level at Cikapundung river was reasonable, with calculating the water quality status, the potential polutions domestic sector. Water quality status is determined by using pollution index method and potential pollution load of Cikapundung River using domestic polution emission factor approach. Result of pollutant index calculation Cikapundung River at 2016 in dry months has severe polluted water quality. Cikapundung watershed contaminated with domestic waste in the calculation of polluted pollutant potency in 2016 by 25.383,89 Kg / day TSS, 17,537.96 kg / day BOD, 18.461.01 kg / day COD, 889.97 kg / day N-Total and 96.92 Kg / day P-Total.Keywords: Pollution Load, Cikapundung Domestic, Water.

In the first paper of this two-part series on the development of a water sustainability index for West Java, a conceptual framework of West Java Water Sustainability Index (WJWSI) was developed. It consists of three main parts: components, indicators/sub-indicators and threshold values. This second paper of the series presents the application of the Delphi technique, followed by in-depth interviews with selected key experts, to refine the conceptual WJWSI framework. The Delphi application includes the design of the questionnaires, the selection of respondents, the distribution and collection of the completed questionnaires and the analysis of data. After Round One of the Delphi application, the respondents reached consensus for all proposed components in the conceptual framework. However, some modifications to the components were also suggested by few respondents. Regarding the indicators/sub-indicators, consensus for 9 of the proposed 12 indicators was reached, and 5 new indicators were suggested. For the threshold values, consensus was reached for threshold values of 5 indicators. In Round Two of the Delphi application, respondents were asked questions related to results from Round One, which include the modification on the components, indicators/sub-indicators which have not been agreed, and newly suggested indicators/sub-indicators and threshold values. Results of Round Two show that modifications on the components were agreed, and consensus was reached for 8 out of the proposed 9 indicators/sub-indicators. In terms of its components and indicators, the framework was then finalised in the in-depth interview with four key experts, selected from different respondent categories. For the threshold values not yet finalised, further study will be carried out, as there was not much input from the respondents in the Delphi application and the in-depth interview.

Water sustainability indices have been recently used to measure the sustainability of water resources within a catchment. Developing a sustainability index involves various steps, some of which have uncertainties associated with them. For the recently developed West Java Water Sustainability Index (WJWSI), three sources of uncertainties were identified, namely uncertainties in the thresholds of noncategorical indicators and sub-indicators, in the weighting schemes, and in the aggregation methods. This paper presents the uncertainty and sensitivity analysis of WJWSI, based on the application of WJWSI to Citarum catchment in West Java, Indonesia. The results of the uncertainty analysis, measured by the coefficient of variation of the thresholds and the sub-indices, indicates that minimum thresholds of Land Use Changes, Coverage, Education, Poverty, Health Impact and Sanitation, and the maximum threshold of Water Quality have higher variation when compared to variation of the other thresholds. The results of the sensitivity analysis, measured by the correlation coefficients between the final index and the thresholds, indicate that changes in the thresholds of WJWSI indicators have not significantly affected the sub-index values of most indicators and sub-indicators. The sensitivity analysis also concluded that either the equal or non-equal weighting scheme can be used for future use of the aggregation of WJWSI indicators and sub-indicators, as changes from equal to non-equal weighting scheme did not significantly affect the final index. However, it was found that the final index values were most sensitive to the aggregation method used (i.e. arithmetic and geometric methods), shown by the significant changes in the final index value when the aggregation method was changed from arithmetic to geometric. The uncertainty and sensitivity analysis presented in this study will not just assist in the efficient use of the WJWSI, but will also help undertake similar analysis for other indices.