Geography

what! ? Luzhou was submerged by Taipei Lake before? So why does it appear again now?

Too many aliases? What is the meaning behind it?

Regarding the history of Luzhou being bullied by water, can you give full play to your sense of justice and explore with us what is the festival of water and Luzhou?

Man of few words! Let's keep watching~

Luzhou terrain

Luzhou City is located on the west bank of the lower reaches of the Danshui River. Surrounded by river water, there are no mountains around the area.

Luzhou faces Shilin across the Danshui River. It is surrounded by the embankment of the Erzhong Floodway to the west, Wugu Township on the other side of the floodway, and Sanchong adjacent to Yamu Port to the southeast. The shape of Luzhou is a slight parallelogram, surrounded by river water, with obvious boundaries. Its area is very small, only slightly larger than Yonghe City, and the area is the second smallest district in New Taipei City. If you look at the Taipei Basin, Luzhou is located in the northwestern part of the Taipei Basin, close to the junction of the Tatun Volcano Group and the Linkou Platform.

資料來源:蘆洲區公所-蘆洲市志

Luzhou old place names

Luzhou has many old place names, such as Heshangzhou, Luzhou, Xiancaopu, and Zhongzhoupu.

He Shang Zhou: It was the original name of Luzhou.From the geographical landscape, the name is related to the sandbank on the Danshui River in the early period of Luzhou, so the ancestors named it Heshangzhou.
Monk Continent: It was the name given to Luzhou during the Qing Dynasty. During the initial development, the monk Mei Fu applied to the government for permission to reclaim the area, and he used this place as the temple's oil funds. Many monks wanted to visit Luzhou for recreation, so they set up a "one mansion" to collect rent (rent-collecting houses), which was then called "Shangzhou ''.
Heron Continent：After Taiwan was ruled by the Japanese, the Japanese wantede to change the name because they the name was very indecent. Due to large number of egrets in the area close to the sandbanks, it was abbreviated as " Heron Continent " (including the Sanchong District).
Luzhou: In the 36th year of the Republic of China, after the separation of Sanchong and Luzhou, the name was changed to "Luzhou Township"

Geology

The bitter history of Luzhou once lying under the shell mound

The geographical history of Luzhou can be traced back to 1.8 million years ago. Due to the influence of plate movement, the northwestern part of Taiwan showed a northeast-southwest fault. In the subsequent geological ages of the Taipei Basin, these three major faults stretched the stratum, which caused the Taipei area, which was originally a hilly terrain, to sink and become a basin, which then gradually became the sandbar terrain in the Luzhou area at the bottom of the Taipei Basin today. The stratum in the Taipei Basin in the Luzhou area can be divided into 5 layers, from bottom to top they are the Linkou gravel layer, the Xinzhuang layer, the Jingmei layer, the Songshan layer, and the topsoil sedimentary layer. The Linkou gravel layer is the bottom layer of the entire Taipei Basin. At the time when the Taipei area had not yet become a hilly terrain, the Linkou platform was a coastal area. This is the bottom structure of the quaternary sedimentary layer in the Taipei Basin, the "Linkou gravel layer".

Later about 60,000 years ago, fault activity occurred in the Taipei area, and a new Shanchiao fault was generated along the Xinzhuang Fault. As a result, the southeast of the Linkou area sank and the Linkou platform formed, and the Shanjiao Fault, the Tatun Volcano Group, and the Taipei Fault The surrounding hilly land fell relatively, forming the foundation of the early Taipei Basin. After the formation of the early Taipei Basin, the rivers that were originally injected into the basin were blocked under the fault cliffs of the Shanjiao Fault, submerging the area of Mount Tai and Xinzhuang, forming the "Xinzhuang Lake''. At this time, the Luzhou area was located at the bottom of the lake, Xinzhuang Lake. The sedimentary layer of this period is called the "Xinzhuang layer", which is the second layer of the basin bottom. While the basin was sinking, the Guxindian River continued to transport sediments and deposited a fan-shaped gravel layer on the southeastern side of the basin, extending westward to cover the Xinzhuang layer, which is the third layer of the basin bottom. Later, due to the collapse of the Taipei Basin, the erosion base level was lowered. The Keelung River, which originally flowed to the northeast into the sea, and the Dahan River, which originally flowed to the northwest into the sea, were seized by rivers in the basin, so all the water and sediment of the two rivers flowed into Taipei. In the basin, the accumulation of water in the basin formed the "Songshan Period Taipei Freshwater Lake '', and a large amount of sediment constitutes the fourth layer of the Taipei Basin-the "Songshan Layer". After that, the sea level rose and the sea water intruded into the Taipei Basin, and the freshwater lake was salted into the "Songshan Period Taipei Salt Lake ''.

Later, the edge of the basin near Guandu was cut through by the lake, and the lake water flowed out to the open sea, and the bottom of the lake became dry. About 4,500 years ago, the basin tilted from southeast to northwest, and the northwest of the basin became a swamp area. At this time, the Luzhou area was part of the northwest swamp area. Since the end of the Pleistocene, the Taipei Basin has experienced three transgressions and retreats. Each transgression will form a large lake, and each retreat will gradually reveal the land at the bottom of the basin. About 3,500 years ago, the land declined slightly, and seawater invaded Guandu again from Guandu. The northwestern part of the basin was submerged by seawater, and the rivers in the southeast remained freshwater. It formed at the highest tide during the invasion period, so it was called "Taipei Lake in the Yuanshan Shell Mound Period". During this period, the Luzhou area was submerged again. Between 2,500 and 2,000 years ago, the land rose and then fell again, causing another transgression.

資料來源:蘆洲區公所-蘆洲市志-地理篇-臺北盆地及其周圍的斷層（改繪自中央大學編《「臺北盆地地下地質與工程環境綜合調查研究」成果發表會論文集》）

Hydrology

Luzhou where success lies in water, failure also lies in water

Luzhou is close to the main tributary of the Danshui River. After silting into land from the bottom of the big lake, the land was initially marsh wetlands. The watercourses and ditches were dense like cobwebs. These four hydrological elements are all deeply restricted by the various topographical forces of the Danshui river system.

It goes without saying that the characteristics of the freshwater river system have become a factor for affecting the hydrological environment of Luzhou. The Taipei Basin has a rainy climate all year round, providing abundant water sources for freshwater rivers. The fertile alluvial plains around Luzhou have created prosperous agricultural settlements. Rivers and canals crisscross the fields, forming a dense shipping network.

The riverside area on the north side of Luzhou is located at the top part of the convex bank of the Danshui River's large meandering belt, and it has a strong accumulation effect. The silt flow carried by the Danshui River from the upper reaches to the meandering zone of Luzhou, the east bank is Shezi Island, which belongs to the concave bank eroded by the currents. The river water is deep, the river bank foundation is attacked by the current, and the river terraces collapse easily. As the rapids wash away, the river bank gradually recedes; while the west bank of Luzhou is a convex bank of the accumulation surface. The flow rate is slower and the river water is shallow. The sediment is easy to quickly precipitate and accumulate. The river bank will continue to accumulate to form sand, so the river bank Gradually advances into the river. Located on the convex bank of the large meandering belt, Xinzhuangtou Qianpu, Erchongpu, Sanchongpu and Luzhou, this crescent-shaped zone is a sandbar land formed by sedimentation of the meandering sedimentation of the Danshui River.The " Fertile Crescent " in the lower reaches of the Tamsui River has flat terrain and fertile soil, suitable for farming. The coasts are mostly soft and silt land. The waters are too shallow to build large piers, which is not conducive to the development of shipping.

The hydrological environment in Luzhou has a characteristic. The dense swamps along the river have an extremely important position in nature. Although they are unlikely to become a breeding ground for infectious diseases, they also have the function of reconciling the hydrological environment. The marsh wetlands beside river banks or streams can adjust the water volume during showers or flooding periods, temporarily accumulate floods, thereby reducing the damage these cause, and slowing down the flow of floods to prevent river banks from being eroded. In addition, it can also absorb and dilute the pollutants in the river to help purify the water quality, and the wetland is also a natural source of groundwater replenishment, which has the function of alleviating the occurrence of drought.

On the other hand, swamp wetland is also an important habitat for a variety of wild animals and plants. The ecology is diverse and full of vitality. A swamp wetland forms an ecosystem of its own and plays an important role in the balance of regional ecology. However, these marsh wetlands have disappeared due to the rapid urbanization in recent years, and they have been filled up into construction sites or garbage dumps, leading to the disappearance of various biological habitats and the weakening of wetland functions. The urban plan was dumped and filled and became part of the rezoned area. As a result, there was no place to temporarily store the waters when the flood came. The hydrological environment in the Luzhou area was out of balance, which intensified the flood disaster. The current Nangangzi rezoning area is already a prosperous scene of tall buildings and many businesses, but at the same time it has lost the natural barrier that used to protect the safety of the people of Luzhou by marsh wetlands.

Weather

The ever-changing climate

The Luzhou area has a rainy climate throughout the year. The accumulation of rainfall in summer mainly depends on the presence or absence of torrential rains brought by typhoons. In winter, there is stable rainwater supply brought by the northeast monsoon. The rainfall in winter is better than that in summer in that it's more balanced. Under this kind of summer and winter climates, lowland Luzhou, where water will accumulate after more than 30 minutes of continuous rain, is shrouded in the shadow of floods from the beginning to the end of the year.

The climate of Luzhou is a warm and humid subtropical monsoon climate, which is the same type as the basin bottom zone of the Taipei Basin. The annual rainfall is between 1,500 and 2,000 mm. Summer rains more than winter, but winter is not completely dry. The climate of Luzhou is characterized by high temperature and rain in summer, low temperature, and rain in winter, with an average annual temperature of about 22 degrees Celsius, and most of the temperature is subtropical. Luzhou is located in a plain with almost no terrain barrier, which helps the wind to accelerate. The wind blowing from the basin edge mountain is strong. The summer and autumn typhoons and the northeast monsoon in winter are more intense. Therefore, windbreak forests were planted around Luzhou farmland in the past. To prevent wind damage, it is a special landscape on the ground. The low and flat terrain is the basis of the natural environment for the residents to suffer from floods over the years, and the typhoons and rain that visit Taiwan every summer and autumn are the culprits of the persistent water accumulation in Luzhou in the basin. Under the dual effects of low-lying terrain and rainy climate, Luzhou is destined to become a land that is regularly flooded with water.

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