It might be the size of Rhode Island.
" Their study, published last year in the Journal of Climate, found that between 1988 and 1996, urban land cover in the Pearl River Delta increased 300 percent -- the equivalent of paving an area the size of Rhode Island in less than a decade. Meanwhile, during the dry winter months (the subtropical region's summer is influenced by the Asian monsoon cycle), rainfall declined. The team created a statistical model linking urban growth with winter rainfall; they found that each percentage point in growth correlated with a decrease of 2.44 milli-meters in rainfall."
I'm not obsessed enough to try to fact check this.
Link to Yale School of Forestry and Environment Magazine