4.8. THE BARAYS OF ANGKOR The city of Angkor was the capital of the Kmer Empire from the 8th to the 14th century. It was situated where today we find Cambodia, together with the delta of the river Mekong and some 400 km to the north of the capital Phnom Penh. The name of the city came from the Sanskrit "nagara", which means: Capital city. The emplacement of the area was of great importance for the trade between Iran, India, China and the former Mediterranean provinces of the Roman Empire. Thanks to its good commercial relations, it quickly came to be a city of great economic, cultural and technological prosperity; and as a consequence of the great prosperity, the population increased. Until the 9th century it was a weak empire formed by many independent powers that was known as Andripura, but at the beginning of the 9th century, the King Joyavarman II conquered the area called Aninditapura and founded the Kmer Empire. During the reign of Indravaraman I, in the year 880, the capital moved to Harihalaya 15 km from where Angkor can be found today. Its population was formed by 100,000 people that obtained 4,00 Tm of rice per year. In this period, the temple Preah-Ko was built, the centre of Bakong with its five level pyramid and the first Baray. The Baray were rectangular pools of variable dimensions that collected water for the irrigation of rice and also regular annual inundations caused by the monsoon climate. This first Baray had dimensions of 3.8 km by 1 km y a capacity for 10 million cubic meters. These dimensions allowed for enough water to fill 40 km2 of the rice cultivation. With its system of canals fed from the river Stung Rolous, the Kmer Empire managed to multiply its food generation capacity and became capable of obtaining 130 Tm/Km2 per year in 3 harvests. In the year 897, Yasovarman I started the construction of a second Baray called "oriental". In the middle of it, an Island, Loley was built. On the island a Asharama dedicated to the ancestors of the king was constructed. This Baray was five times bigger that the first, 7 km by 2.5 with a capacity of 50 million m3 of water that was fed from the river Stung Siem Reap that made possible the farming of 200 more km2 of land. This King also moved the capital to what is now considered the first Angkor. The city was created and protected by a wall of 4 km by 4 km. Finally, in the year 1010, Sűryavarman I built a third Baray called "occidental", bigger than the first two, 8 km by 2 km, fed by the river Stung Puok with 57 million m3 of water. The farmable area was increased by an additional 100 km2. The following ruling Kings reorganised the Baray but without increasing its capacity. Gradually, at a rate of 0.1% a year of its capacity, the Baray stopped being feasible owing to an increase of land and a decrease in its capacity to store water. With this model we will study the evolution of the principle parameters of the system and its variables. LINKS: Theory and Practical Exercises of System Dynamics System Dynamics Online Courses Building Models in Ecology Building models with Vensim Other resources in System Dynamics Boletín de Dinámica de Sistemas