Water in urbanregions 157Lakeshores
[W5]Half of the regions with a lake(s) present have natural vegetation around
90--100 % of lake shorelines, while nearly half have <30 % of the shoreline length with
natural vegetation(Figure6.7).
Generally lakes, unlike dammed reservoirs, are scarce in urban regions, and
therefore of special importance for recreation, visual quality, and biodiversity.
Continuous natural vegetation around lakeshores is particularly important for
maintaining high water quality. In those regions with low protection around
shorelines, avoiding development, even dispersed development, is a key to main-
taining clear water, natural aquatic ecosystems, fish populations, and associated
recreation.
Slopes around cities
[W6]More than half of the cities with nearby hillslopes or mountain slopes facing
the cityhave90--100%naturalvegetationcoverontheslopes(Figure6.12).
Maintaining natural vegetation on these slopes provides many benefits,
including high visual quality, good recreation opportunities, and rich biodi-
versity, all close to the metropolitan area. The vegetation also minimizes soil
erosion, mudslides, sediment accumulation, and flood hazard. Forest on slopes
provides cool air that on still nights drains downward and helps ventilate a city
by pushing out hot air and pollutants. In dry climates, vegetation on nearby
slopes increases the fire hazard. ‘‘Skyline conservation” on slopes surrounding
thecity has deep roots and cultural significance in Korea and Japan (Im1992,
Bengston and Youn2006). Where few nearby city-facing slopes are present, pro-
tecting them with natural vegetation is apriority.
[W7]Nearly 30 % ofthecities with nearby city-facing slopes have them only 25--50 % covered
with natural vegetation(Figure6.12).
As implied in the preceding case, the paucity of protective natural vegeta-
tion on these slopes reduces benefits and poses increased hazards. Avoiding
additional development is a priority. Fine-scale improvements on the developed
slopes involving water, soil, and vegetation should have a significant effect. Also,
gradually removing buildings on the most inappropriate sites should help.
[W8]Cities with more surrounding city-facing slopes generally have a greater percentage
cover of natural vegetation on them, whereas few nearby slopes near a city tend to be
much built up(Figure6.12).
In the case of few nearby city-facing slopes, their scarce natural resources
are much degraded. Avoiding future development, rigorously implementing