## 1 Introduction  
The ability of irrigation agriculture to support large populations and underwrite the agrarian economy of New and Old-World state level societies has long been recognized [1; 2; 3; 4; 5; 6; 7; 8; 9; 10; 11]. While the interplay between social institutions, political organizations and the agrarian economy based upon water engineering resources for urban and agricultural use has been considered in these and many other publications, the water engineering technology underlying the success of agricultural structures in sustaining large urban populations and demographic growth remains in the initial stages of discovery. Given the different ecologies and climate extremes at many different Old and New World archeological sites, different water engineering strategies applied to agricultural systems required different levels of inventiveness to sustain an associated population centers' economic base. Of interest in New World studies of pre-Columbian societies of South America are the raised-field agricultural systems of the (c. 500-1100 CE) Tiwanaku society located adjacent to Lake Tticaca in the atiplano region (-3810 masl) of Bolivia (Figure 1). Early studies of the raised-field systems in this area [12; 13; 14; 15; 16; 17; 18; 19; 20; 21; 22; 23; 24; 25; 26] describe their discovery but not the water engineering technology involved in their use to protect crops from altiplano freezing events. The present study serves to add additional discoveries and commentary to our earlier research [12] through further ANSYS analysis studies focused on the Bolivian Pampa Koani area of \(\sim\)14,000 hectares of early cultivation activity, which supported the urban population of Tiwanaku society. Research was undertaken in two raised-field segments to examine their method of construction and modifications from Lake Titicaca height excursions over \(\sim\)1700 years since the initial construction to determine the water and heat transfer engineering underlying the construction and usage of Tiwanaku agricultural raised fields [27; 28; 29; 30; 31; 32]. Field excavations in ancient raised fields, along with investigations of local topography and the groundwater aquifer supporting the restored raised-field systems, were conducted to provide the input data for ANSYS finite element analysis to acquire the knowledge of how ancient Tiwanaku water engineers understood the hydraulic and heat transfer science, which supported the agricultural productivity of their raised-field agricultural systems--albeit through their own perspectives of the techniques required to achieve knowledge of thermo-fluid engineering effects. As is common in archeological studies involving ancient technologies, the results of the ancient engineers' accomplishments are apparent but not the knowledge underlying their inventive engineering steps used to achieve the final results. While modern analysis methods reveal details of the design and function of ancient raised-field agriculture and its engineering base, the analytic exposition presented explores the necessary engineering, which ancient Tiwanaku water engineers understood in their own terms for their indigenous version of hydraulic and thermal science.  
Figure 1: The Pampa Koani raised-field study area located \(\sim\)5 km north of urban Tiwanaku.