INGENIEUR
by the National Water Council on July 29 of that same year . It was part of a strategy to reinforce coordination between the Federal , State and Local Governments towards managing the river basins effectively and holistically . To date , 37 IRBM plans have been completed . These cover more than 70 % of Peninsular Malaysia and 25 more IRBM plans will be completed under the Twelfth Malaysia Plan which includes Sarawak and Sabah .
DID has continuously been promoting the adoption of IRBM plans to the relevant stakeholders . In the latest development , the National Water Council in April 2021 has sanctioned that the IRBM plan be a mandatory reference in land development planning at the state and district levels .
Objectives and Key Elements
IRBM is geared towards maximising the economic and social benefits derived from water resources while maintaining and amplifying the water resources ecosystem . The IRBM plan synergises policies , programmes and practices to achieve four main objectives , namely : 1 . To guarantee enough water ; 2 . To guarantee clean water ; 3 . To minimise flood risk ; and 4 . To improve and conserve the environment The IRBM plan encompasses planning , implementation and consolidation of strategies . It frames the blueprint of necessary activities or action plans to sustainably exploit water resources , improve and conserve the river basins in harmony with economic needs . The IRBM plan also defines the enablers for successful plan execution , which include financial , institutional governance and legal considerations .
Formulating an IRBM Plan
The formulation of an IRBM plan begins with robust primary data input that includes rainfall , river levels and flows , river engineering surveys and land use . The operational data of water extraction and discharge released into the rivers , such as sewerage treatment plants and water intakes , are collected to facilitate numerical analysis . An extensive hydrodynamic analysis of the river system , including water balance analysis , high and low flow river analysis , water quality analysis and sediment transport analysis are required when formulating an IRBM plan .
The results of the extensive hydrodynamic analysis are grouped into four major components :
Water accounting and availability This analysis determines the present state of water availability and its prospect in meeting the water demands within the river basin . The IRBM plan explores the opportunity to increase reserve water availability within the river basin , by either introducing dual-purpose structures or alternative resources .
Flood risk assessment This assessment is based on the current and projected land use for the river basin . Based on the 100 ARI critical storm analysis , an understanding of the flow behaviour is developed , and conceptual flood mitigation measures are proposed based on the flood projection . Existing land use information and development plans allow non-structural options to be implemented , such as the gazetting of flood plains and adjacent state land for future construction of off-river storage ponds .
Coastal The sediment transport analysis assesses the risk of possible coastal erosion at the coastline if sediment flow towards the sea is inhibited .
River water quality Published data from the Department of Environment on river water quality is the primary data used as a baseline in water quality modelling . Pollution mapping is performed to identify the contributing pollutants to the river water body . Simulations during low and normal flows are conducted to determine the river carrying capacity . Appropriate pollution reduction strategy for the river basin is then proposed to achieve the desired Class II river water quality .
Aside from the inventory and engineering analyses of the water resources , qualitative analysis is conducted through surveys , interviews , and stakeholder engagements to better understand social behaviour , acceptance and
8 VOL 87 JULY-SEPTEMBER 2021