A substantial portion of the Valley’s population decline occurred in the piedmont zones within a 20 km radius of Monte Albán , the area that had experienced the most substantial growth during the preceding Monte Albán I phase. Both hamlets and village level “administrative centers” being abandoned and “replaced” by new settlement located in the alluvial plain.
Blanton, et. al. ( Blanton, et. al. ‘93:86, interpret this population decline/shift as the result of “curtailment of the piedmont strategy”. As I suggested earlier, The term ‘strategy’ could be misleading. The most straight forward explanation of the abandonment of piedmont agriculture would appear to be that , with fewer people in the Valley, there is now room in the alluvial plain for anybody who wants it. Of course, this is only satisfactory it we can explain population decline independently of the abandonment of piedmont agriculture. Some combination of anthropogenic environmental degradation and climate change might serve to explain both the abandonment of piedmont agriculture and population decline.
More specifically, it would be interesting to know the extent to which piedmont locations depend on ground water sources for potable water during the dry season. It could be that during the rainy season, there is surface water for agriculture, but springs are relied on for potable water during the dry season This should be easy to determine from present and/or historic sources. Were this dependence to be significant, then one should look at the possibility climate driven fluctuations in ground water availability influencing the suitability of the piedmont for human occupation. Depending on the nature of the aquifer, these fluctuations might lag behind the climatic conditions that cause them by hundreds of years.
